Fix a compiler warning in initStringInfo().

[pgsql.git] / src / backend / utils / mmgr / mcxt.c

/*-------------------------------------------------------------------------
 *
 * mcxt.c
 *        POSTGRES memory context management code.
 *
 * This module handles context management operations that are independent
 * of the particular kind of context being operated on.  It calls
 * context-type-specific operations via the function pointers in a
 * context's MemoryContextMethods struct.
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        src/backend/utils/mmgr/mcxt.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_internal.h"
#include "utils/memutils_memorychunk.h"


static void BogusFree(void *pointer);
static void *BogusRealloc(void *pointer, Size size, int flags);
static MemoryContext BogusGetChunkContext(void *pointer);
static Size BogusGetChunkSpace(void *pointer);

/*****************************************************************************
 *        GLOBAL MEMORY                                                                                                                  *
 *****************************************************************************/
#define BOGUS_MCTX(id) \
        [id].free_p = BogusFree, \
        [id].realloc = BogusRealloc, \
        [id].get_chunk_context = BogusGetChunkContext, \
        [id].get_chunk_space = BogusGetChunkSpace

static const MemoryContextMethods mcxt_methods[] = {
        /* aset.c */
        [MCTX_ASET_ID].alloc = AllocSetAlloc,
        [MCTX_ASET_ID].free_p = AllocSetFree,
        [MCTX_ASET_ID].realloc = AllocSetRealloc,
        [MCTX_ASET_ID].reset = AllocSetReset,
        [MCTX_ASET_ID].delete_context = AllocSetDelete,
        [MCTX_ASET_ID].get_chunk_context = AllocSetGetChunkContext,
        [MCTX_ASET_ID].get_chunk_space = AllocSetGetChunkSpace,
        [MCTX_ASET_ID].is_empty = AllocSetIsEmpty,
        [MCTX_ASET_ID].stats = AllocSetStats,
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_ASET_ID].check = AllocSetCheck,
#endif

        /* generation.c */
        [MCTX_GENERATION_ID].alloc = GenerationAlloc,
        [MCTX_GENERATION_ID].free_p = GenerationFree,
        [MCTX_GENERATION_ID].realloc = GenerationRealloc,
        [MCTX_GENERATION_ID].reset = GenerationReset,
        [MCTX_GENERATION_ID].delete_context = GenerationDelete,
        [MCTX_GENERATION_ID].get_chunk_context = GenerationGetChunkContext,
        [MCTX_GENERATION_ID].get_chunk_space = GenerationGetChunkSpace,
        [MCTX_GENERATION_ID].is_empty = GenerationIsEmpty,
        [MCTX_GENERATION_ID].stats = GenerationStats,
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_GENERATION_ID].check = GenerationCheck,
#endif

        /* slab.c */
        [MCTX_SLAB_ID].alloc = SlabAlloc,
        [MCTX_SLAB_ID].free_p = SlabFree,
        [MCTX_SLAB_ID].realloc = SlabRealloc,
        [MCTX_SLAB_ID].reset = SlabReset,
        [MCTX_SLAB_ID].delete_context = SlabDelete,
        [MCTX_SLAB_ID].get_chunk_context = SlabGetChunkContext,
        [MCTX_SLAB_ID].get_chunk_space = SlabGetChunkSpace,
        [MCTX_SLAB_ID].is_empty = SlabIsEmpty,
        [MCTX_SLAB_ID].stats = SlabStats,
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_SLAB_ID].check = SlabCheck,
#endif

        /* alignedalloc.c */
        [MCTX_ALIGNED_REDIRECT_ID].alloc = NULL,        /* not required */
        [MCTX_ALIGNED_REDIRECT_ID].free_p = AlignedAllocFree,
        [MCTX_ALIGNED_REDIRECT_ID].realloc = AlignedAllocRealloc,
        [MCTX_ALIGNED_REDIRECT_ID].reset = NULL,        /* not required */
        [MCTX_ALIGNED_REDIRECT_ID].delete_context = NULL,       /* not required */
        [MCTX_ALIGNED_REDIRECT_ID].get_chunk_context = AlignedAllocGetChunkContext,
        [MCTX_ALIGNED_REDIRECT_ID].get_chunk_space = AlignedAllocGetChunkSpace,
        [MCTX_ALIGNED_REDIRECT_ID].is_empty = NULL, /* not required */
        [MCTX_ALIGNED_REDIRECT_ID].stats = NULL,        /* not required */
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_ALIGNED_REDIRECT_ID].check = NULL,        /* not required */
#endif

        /* bump.c */
        [MCTX_BUMP_ID].alloc = BumpAlloc,
        [MCTX_BUMP_ID].free_p = BumpFree,
        [MCTX_BUMP_ID].realloc = BumpRealloc,
        [MCTX_BUMP_ID].reset = BumpReset,
        [MCTX_BUMP_ID].delete_context = BumpDelete,
        [MCTX_BUMP_ID].get_chunk_context = BumpGetChunkContext,
        [MCTX_BUMP_ID].get_chunk_space = BumpGetChunkSpace,
        [MCTX_BUMP_ID].is_empty = BumpIsEmpty,
        [MCTX_BUMP_ID].stats = BumpStats,
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_BUMP_ID].check = BumpCheck,
#endif


        /*
         * Reserved and unused IDs should have dummy entries here.  This allows us
         * to fail cleanly if a bogus pointer is passed to pfree or the like.  It
         * seems sufficient to provide routines for the methods that might get
         * invoked from inspection of a chunk (see MCXT_METHOD calls below).
         */
        BOGUS_MCTX(MCTX_1_RESERVED_GLIBC_ID),
        BOGUS_MCTX(MCTX_2_RESERVED_GLIBC_ID),
        BOGUS_MCTX(MCTX_8_UNUSED_ID),
        BOGUS_MCTX(MCTX_9_UNUSED_ID),
        BOGUS_MCTX(MCTX_10_UNUSED_ID),
        BOGUS_MCTX(MCTX_11_UNUSED_ID),
        BOGUS_MCTX(MCTX_12_UNUSED_ID),
        BOGUS_MCTX(MCTX_13_UNUSED_ID),
        BOGUS_MCTX(MCTX_14_UNUSED_ID),
        BOGUS_MCTX(MCTX_0_RESERVED_UNUSEDMEM_ID),
        BOGUS_MCTX(MCTX_15_RESERVED_WIPEDMEM_ID)
};

#undef BOGUS_MCTX

/*
 * CurrentMemoryContext
 *              Default memory context for allocations.
 */
MemoryContext CurrentMemoryContext = NULL;

/*
 * Standard top-level contexts. For a description of the purpose of each
 * of these contexts, refer to src/backend/utils/mmgr/README
 */
MemoryContext TopMemoryContext = NULL;
MemoryContext ErrorContext = NULL;
MemoryContext PostmasterContext = NULL;
MemoryContext CacheMemoryContext = NULL;
MemoryContext MessageContext = NULL;
MemoryContext TopTransactionContext = NULL;
MemoryContext CurTransactionContext = NULL;

/* This is a transient link to the active portal's memory context: */
MemoryContext PortalContext = NULL;

static void MemoryContextDeleteOnly(MemoryContext context);
static void MemoryContextCallResetCallbacks(MemoryContext context);
static void MemoryContextStatsInternal(MemoryContext context, int level,
                                                                           int max_level, int max_children,
                                                                           MemoryContextCounters *totals,
                                                                           bool print_to_stderr);
static void MemoryContextStatsPrint(MemoryContext context, void *passthru,
                                                                        const char *stats_string,
                                                                        bool print_to_stderr);

/*
 * You should not do memory allocations within a critical section, because
 * an out-of-memory error will be escalated to a PANIC. To enforce that
 * rule, the allocation functions Assert that.
 */
#define AssertNotInCriticalSection(context) \
        Assert(CritSectionCount == 0 || (context)->allowInCritSection)

/*
 * Call the given function in the MemoryContextMethods for the memory context
 * type that 'pointer' belongs to.
 */
#define MCXT_METHOD(pointer, method) \
        mcxt_methods[GetMemoryChunkMethodID(pointer)].method

/*
 * GetMemoryChunkMethodID
 *              Return the MemoryContextMethodID from the uint64 chunk header which
 *              directly precedes 'pointer'.
 */
static inline MemoryContextMethodID
GetMemoryChunkMethodID(const void *pointer)
{
        uint64          header;

        /*
         * Try to detect bogus pointers handed to us, poorly though we can.
         * Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
         * allocated chunk.
         */
        Assert(pointer == (const void *) MAXALIGN(pointer));

        /* Allow access to the uint64 header */
        VALGRIND_MAKE_MEM_DEFINED((char *) pointer - sizeof(uint64), sizeof(uint64));

        header = *((const uint64 *) ((const char *) pointer - sizeof(uint64)));

        /* Disallow access to the uint64 header */
        VALGRIND_MAKE_MEM_NOACCESS((char *) pointer - sizeof(uint64), sizeof(uint64));

        return (MemoryContextMethodID) (header & MEMORY_CONTEXT_METHODID_MASK);
}

/*
 * GetMemoryChunkHeader
 *              Return the uint64 chunk header which directly precedes 'pointer'.
 *
 * This is only used after GetMemoryChunkMethodID, so no need for error checks.
 */
static inline uint64
GetMemoryChunkHeader(const void *pointer)
{
        uint64          header;

        /* Allow access to the uint64 header */
        VALGRIND_MAKE_MEM_DEFINED((char *) pointer - sizeof(uint64), sizeof(uint64));

        header = *((const uint64 *) ((const char *) pointer - sizeof(uint64)));

        /* Disallow access to the uint64 header */
        VALGRIND_MAKE_MEM_NOACCESS((char *) pointer - sizeof(uint64), sizeof(uint64));

        return header;
}

/*
 * MemoryContextTraverseNext
 *              Helper function to traverse all descendants of a memory context
 *              without recursion.
 *
 * Recursion could lead to out-of-stack errors with deep context hierarchies,
 * which would be unpleasant in error cleanup code paths.
 *
 * To process 'context' and all its descendants, use a loop like this:
 *
 *     <process 'context'>
 *     for (MemoryContext curr = context->firstchild;
 *          curr != NULL;
 *          curr = MemoryContextTraverseNext(curr, context))
 *     {
 *         <process 'curr'>
 *     }
 *
 * This visits all the contexts in pre-order, that is a node is visited
 * before its children.
 */
static MemoryContext
MemoryContextTraverseNext(MemoryContext curr, MemoryContext top)
{
        /* After processing a node, traverse to its first child if any */
        if (curr->firstchild != NULL)
                return curr->firstchild;

        /*
         * After processing a childless node, traverse to its next sibling if
         * there is one.  If there isn't, traverse back up to the parent (which
         * has already been visited, and now so have all its descendants).  We're
         * done if that is "top", otherwise traverse to its next sibling if any,
         * otherwise repeat moving up.
         */
        while (curr->nextchild == NULL)
        {
                curr = curr->parent;
                if (curr == top)
                        return NULL;
        }
        return curr->nextchild;
}

/*
 * Support routines to trap use of invalid memory context method IDs
 * (from calling pfree or the like on a bogus pointer).  As a possible
 * aid in debugging, we report the header word along with the pointer
 * address (if we got here, there must be an accessible header word).
 */
static void
BogusFree(void *pointer)
{
        elog(ERROR, "pfree called with invalid pointer %p (header 0x%016llx)",
                 pointer, (unsigned long long) GetMemoryChunkHeader(pointer));
}

static void *
BogusRealloc(void *pointer, Size size, int flags)
{
        elog(ERROR, "repalloc called with invalid pointer %p (header 0x%016llx)",
                 pointer, (unsigned long long) GetMemoryChunkHeader(pointer));
        return NULL;                            /* keep compiler quiet */
}

static MemoryContext
BogusGetChunkContext(void *pointer)
{
        elog(ERROR, "GetMemoryChunkContext called with invalid pointer %p (header 0x%016llx)",
                 pointer, (unsigned long long) GetMemoryChunkHeader(pointer));
        return NULL;                            /* keep compiler quiet */
}

static Size
BogusGetChunkSpace(void *pointer)
{
        elog(ERROR, "GetMemoryChunkSpace called with invalid pointer %p (header 0x%016llx)",
                 pointer, (unsigned long long) GetMemoryChunkHeader(pointer));
        return 0;                                       /* keep compiler quiet */
}


/*****************************************************************************
 *        EXPORTED ROUTINES                                                                                                              *
 *****************************************************************************/


/*
 * MemoryContextInit
 *              Start up the memory-context subsystem.
 *
 * This must be called before creating contexts or allocating memory in
 * contexts.  TopMemoryContext and ErrorContext are initialized here;
 * other contexts must be created afterwards.
 *
 * In normal multi-backend operation, this is called once during
 * postmaster startup, and not at all by individual backend startup
 * (since the backends inherit an already-initialized context subsystem
 * by virtue of being forked off the postmaster).  But in an EXEC_BACKEND
 * build, each process must do this for itself.
 *
 * In a standalone backend this must be called during backend startup.
 */
void
MemoryContextInit(void)
{
        Assert(TopMemoryContext == NULL);

        /*
         * First, initialize TopMemoryContext, which is the parent of all others.
         */
        TopMemoryContext = AllocSetContextCreate((MemoryContext) NULL,
                                                                                         "TopMemoryContext",
                                                                                         ALLOCSET_DEFAULT_SIZES);

        /*
         * Not having any other place to point CurrentMemoryContext, make it point
         * to TopMemoryContext.  Caller should change this soon!
         */
        CurrentMemoryContext = TopMemoryContext;

        /*
         * Initialize ErrorContext as an AllocSetContext with slow growth rate ---
         * we don't really expect much to be allocated in it. More to the point,
         * require it to contain at least 8K at all times. This is the only case
         * where retained memory in a context is *essential* --- we want to be
         * sure ErrorContext still has some memory even if we've run out
         * elsewhere! Also, allow allocations in ErrorContext within a critical
         * section. Otherwise a PANIC will cause an assertion failure in the error
         * reporting code, before printing out the real cause of the failure.
         *
         * This should be the last step in this function, as elog.c assumes memory
         * management works once ErrorContext is non-null.
         */
        ErrorContext = AllocSetContextCreate(TopMemoryContext,
                                                                                 "ErrorContext",
                                                                                 8 * 1024,
                                                                                 8 * 1024,
                                                                                 8 * 1024);
        MemoryContextAllowInCriticalSection(ErrorContext, true);
}

/*
 * MemoryContextReset
 *              Release all space allocated within a context and delete all its
 *              descendant contexts (but not the named context itself).
 */
void
MemoryContextReset(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));

        /* save a function call in common case where there are no children */
        if (context->firstchild != NULL)
                MemoryContextDeleteChildren(context);

        /* save a function call if no pallocs since startup or last reset */
        if (!context->isReset)
                MemoryContextResetOnly(context);
}

/*
 * MemoryContextResetOnly
 *              Release all space allocated within a context.
 *              Nothing is done to the context's descendant contexts.
 */
void
MemoryContextResetOnly(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));

        /* Nothing to do if no pallocs since startup or last reset */
        if (!context->isReset)
        {
                MemoryContextCallResetCallbacks(context);

                /*
                 * If context->ident points into the context's memory, it will become
                 * a dangling pointer.  We could prevent that by setting it to NULL
                 * here, but that would break valid coding patterns that keep the
                 * ident elsewhere, e.g. in a parent context.  So for now we assume
                 * the programmer got it right.
                 */

                context->methods->reset(context);
                context->isReset = true;
                VALGRIND_DESTROY_MEMPOOL(context);
                VALGRIND_CREATE_MEMPOOL(context, 0, false);
        }
}

/*
 * MemoryContextResetChildren
 *              Release all space allocated within a context's descendants,
 *              but don't delete the contexts themselves.  The named context
 *              itself is not touched.
 */
void
MemoryContextResetChildren(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));

        for (MemoryContext curr = context->firstchild;
                 curr != NULL;
                 curr = MemoryContextTraverseNext(curr, context))
        {
                MemoryContextResetOnly(curr);
        }
}

/*
 * MemoryContextDelete
 *              Delete a context and its descendants, and release all space
 *              allocated therein.
 *
 * The type-specific delete routine removes all storage for the context,
 * but we have to deal with descendant nodes here.
 */
void
MemoryContextDelete(MemoryContext context)
{
        MemoryContext curr;

        Assert(MemoryContextIsValid(context));

        /*
         * Delete subcontexts from the bottom up.
         *
         * Note: Do not use recursion here.  A "stack depth limit exceeded" error
         * would be unpleasant if we're already in the process of cleaning up from
         * transaction abort.  We also cannot use MemoryContextTraverseNext() here
         * because we modify the tree as we go.
         */
        curr = context;
        for (;;)
        {
                MemoryContext parent;

                /* Descend down until we find a leaf context with no children */
                while (curr->firstchild != NULL)
                        curr = curr->firstchild;

                /*
                 * We're now at a leaf with no children. Free it and continue from the
                 * parent.  Or if this was the original node, we're all done.
                 */
                parent = curr->parent;
                MemoryContextDeleteOnly(curr);

                if (curr == context)
                        break;
                curr = parent;
        }
}

/*
 * Subroutine of MemoryContextDelete,
 * to delete a context that has no children.
 * We must also delink the context from its parent, if it has one.
 */
static void
MemoryContextDeleteOnly(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));
        /* We had better not be deleting TopMemoryContext ... */
        Assert(context != TopMemoryContext);
        /* And not CurrentMemoryContext, either */
        Assert(context != CurrentMemoryContext);
        /* All the children should've been deleted already */
        Assert(context->firstchild == NULL);

        /*
         * It's not entirely clear whether 'tis better to do this before or after
         * delinking the context; but an error in a callback will likely result in
         * leaking the whole context (if it's not a root context) if we do it
         * after, so let's do it before.
         */
        MemoryContextCallResetCallbacks(context);

        /*
         * We delink the context from its parent before deleting it, so that if
         * there's an error we won't have deleted/busted contexts still attached
         * to the context tree.  Better a leak than a crash.
         */
        MemoryContextSetParent(context, NULL);

        /*
         * Also reset the context's ident pointer, in case it points into the
         * context.  This would only matter if someone tries to get stats on the
         * (already unlinked) context, which is unlikely, but let's be safe.
         */
        context->ident = NULL;

        context->methods->delete_context(context);

        VALGRIND_DESTROY_MEMPOOL(context);
}

/*
 * MemoryContextDeleteChildren
 *              Delete all the descendants of the named context and release all
 *              space allocated therein.  The named context itself is not touched.
 */
void
MemoryContextDeleteChildren(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));

        /*
         * MemoryContextDelete will delink the child from me, so just iterate as
         * long as there is a child.
         */
        while (context->firstchild != NULL)
                MemoryContextDelete(context->firstchild);
}

/*
 * MemoryContextRegisterResetCallback
 *              Register a function to be called before next context reset/delete.
 *              Such callbacks will be called in reverse order of registration.
 *
 * The caller is responsible for allocating a MemoryContextCallback struct
 * to hold the info about this callback request, and for filling in the
 * "func" and "arg" fields in the struct to show what function to call with
 * what argument.  Typically the callback struct should be allocated within
 * the specified context, since that means it will automatically be freed
 * when no longer needed.
 *
 * There is no API for deregistering a callback once registered.  If you
 * want it to not do anything anymore, adjust the state pointed to by its
 * "arg" to indicate that.
 */
void
MemoryContextRegisterResetCallback(MemoryContext context,
                                                                   MemoryContextCallback *cb)
{
        Assert(MemoryContextIsValid(context));

        /* Push onto head so this will be called before older registrants. */
        cb->next = context->reset_cbs;
        context->reset_cbs = cb;
        /* Mark the context as non-reset (it probably is already). */
        context->isReset = false;
}

/*
 * MemoryContextCallResetCallbacks
 *              Internal function to call all registered callbacks for context.
 */
static void
MemoryContextCallResetCallbacks(MemoryContext context)
{
        MemoryContextCallback *cb;

        /*
         * We pop each callback from the list before calling.  That way, if an
         * error occurs inside the callback, we won't try to call it a second time
         * in the likely event that we reset or delete the context later.
         */
        while ((cb = context->reset_cbs) != NULL)
        {
                context->reset_cbs = cb->next;
                cb->func(cb->arg);
        }
}

/*
 * MemoryContextSetIdentifier
 *              Set the identifier string for a memory context.
 *
 * An identifier can be provided to help distinguish among different contexts
 * of the same kind in memory context stats dumps.  The identifier string
 * must live at least as long as the context it is for; typically it is
 * allocated inside that context, so that it automatically goes away on
 * context deletion.  Pass id = NULL to forget any old identifier.
 */
void
MemoryContextSetIdentifier(MemoryContext context, const char *id)
{
        Assert(MemoryContextIsValid(context));
        context->ident = id;
}

/*
 * MemoryContextSetParent
 *              Change a context to belong to a new parent (or no parent).
 *
 * We provide this as an API function because it is sometimes useful to
 * change a context's lifespan after creation.  For example, a context
 * might be created underneath a transient context, filled with data,
 * and then reparented underneath CacheMemoryContext to make it long-lived.
 * In this way no special effort is needed to get rid of the context in case
 * a failure occurs before its contents are completely set up.
 *
 * Callers often assume that this function cannot fail, so don't put any
 * elog(ERROR) calls in it.
 *
 * A possible caller error is to reparent a context under itself, creating
 * a loop in the context graph.  We assert here that context != new_parent,
 * but checking for multi-level loops seems more trouble than it's worth.
 */
void
MemoryContextSetParent(MemoryContext context, MemoryContext new_parent)
{
        Assert(MemoryContextIsValid(context));
        Assert(context != new_parent);

        /* Fast path if it's got correct parent already */
        if (new_parent == context->parent)
                return;

        /* Delink from existing parent, if any */
        if (context->parent)
        {
                MemoryContext parent = context->parent;

                if (context->prevchild != NULL)
                        context->prevchild->nextchild = context->nextchild;
                else
                {
                        Assert(parent->firstchild == context);
                        parent->firstchild = context->nextchild;
                }

                if (context->nextchild != NULL)
                        context->nextchild->prevchild = context->prevchild;
        }

        /* And relink */
        if (new_parent)
        {
                Assert(MemoryContextIsValid(new_parent));
                context->parent = new_parent;
                context->prevchild = NULL;
                context->nextchild = new_parent->firstchild;
                if (new_parent->firstchild != NULL)
                        new_parent->firstchild->prevchild = context;
                new_parent->firstchild = context;
        }
        else
        {
                context->parent = NULL;
                context->prevchild = NULL;
                context->nextchild = NULL;
        }
}

/*
 * MemoryContextAllowInCriticalSection
 *              Allow/disallow allocations in this memory context within a critical
 *              section.
 *
 * Normally, memory allocations are not allowed within a critical section,
 * because a failure would lead to PANIC.  There are a few exceptions to
 * that, like allocations related to debugging code that is not supposed to
 * be enabled in production.  This function can be used to exempt specific
 * memory contexts from the assertion in palloc().
 */
void
MemoryContextAllowInCriticalSection(MemoryContext context, bool allow)
{
        Assert(MemoryContextIsValid(context));

        context->allowInCritSection = allow;
}

/*
 * GetMemoryChunkContext
 *              Given a currently-allocated chunk, determine the MemoryContext that
 *              the chunk belongs to.
 */
MemoryContext
GetMemoryChunkContext(void *pointer)
{
        return MCXT_METHOD(pointer, get_chunk_context) (pointer);
}

/*
 * GetMemoryChunkSpace
 *              Given a currently-allocated chunk, determine the total space
 *              it occupies (including all memory-allocation overhead).
 *
 * This is useful for measuring the total space occupied by a set of
 * allocated chunks.
 */
Size
GetMemoryChunkSpace(void *pointer)
{
        return MCXT_METHOD(pointer, get_chunk_space) (pointer);
}

/*
 * MemoryContextGetParent
 *              Get the parent context (if any) of the specified context
 */
MemoryContext
MemoryContextGetParent(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));

        return context->parent;
}

/*
 * MemoryContextIsEmpty
 *              Is a memory context empty of any allocated space?
 */
bool
MemoryContextIsEmpty(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));

        /*
         * For now, we consider a memory context nonempty if it has any children;
         * perhaps this should be changed later.
         */
        if (context->firstchild != NULL)
                return false;
        /* Otherwise use the type-specific inquiry */
        return context->methods->is_empty(context);
}

/*
 * Find the memory allocated to blocks for this memory context. If recurse is
 * true, also include children.
 */
Size
MemoryContextMemAllocated(MemoryContext context, bool recurse)
{
        Size            total = context->mem_allocated;

        Assert(MemoryContextIsValid(context));

        if (recurse)
        {
                for (MemoryContext curr = context->firstchild;
                         curr != NULL;
                         curr = MemoryContextTraverseNext(curr, context))
                {
                        total += curr->mem_allocated;
                }
        }

        return total;
}

/*
 * Return the memory consumption statistics about the given context and its
 * children.
 */
void
MemoryContextMemConsumed(MemoryContext context,
                                                 MemoryContextCounters *consumed)
{
        Assert(MemoryContextIsValid(context));

        memset(consumed, 0, sizeof(*consumed));

        /* Examine the context itself */
        context->methods->stats(context, NULL, NULL, consumed, false);

        /* Examine children, using iteration not recursion */
        for (MemoryContext curr = context->firstchild;
                 curr != NULL;
                 curr = MemoryContextTraverseNext(curr, context))
        {
                curr->methods->stats(curr, NULL, NULL, consumed, false);
        }
}

/*
 * MemoryContextStats
 *              Print statistics about the named context and all its descendants.
 *
 * This is just a debugging utility, so it's not very fancy.  However, we do
 * make some effort to summarize when the output would otherwise be very long.
 * The statistics are sent to stderr.
 */
void
MemoryContextStats(MemoryContext context)
{
        /* Hard-wired limits are usually good enough */
        MemoryContextStatsDetail(context, 100, 100, true);
}

/*
 * MemoryContextStatsDetail
 *
 * Entry point for use if you want to vary the number of child contexts shown.
 *
 * If print_to_stderr is true, print statistics about the memory contexts
 * with fprintf(stderr), otherwise use ereport().
 */
void
MemoryContextStatsDetail(MemoryContext context,
                                                 int max_level, int max_children,
                                                 bool print_to_stderr)
{
        MemoryContextCounters grand_totals;

        memset(&grand_totals, 0, sizeof(grand_totals));

        MemoryContextStatsInternal(context, 0, max_level, max_children,
                                                           &grand_totals, print_to_stderr);

        if (print_to_stderr)
                fprintf(stderr,
                                "Grand total: %zu bytes in %zu blocks; %zu free (%zu chunks); %zu used\n",
                                grand_totals.totalspace, grand_totals.nblocks,
                                grand_totals.freespace, grand_totals.freechunks,
                                grand_totals.totalspace - grand_totals.freespace);
        else
        {
                /*
                 * Use LOG_SERVER_ONLY to prevent the memory contexts from being sent
                 * to the connected client.
                 *
                 * We don't buffer the information about all memory contexts in a
                 * backend into StringInfo and log it as one message.  That would
                 * require the buffer to be enlarged, risking an OOM as there could be
                 * a large number of memory contexts in a backend.  Instead, we log
                 * one message per memory context.
                 */
                ereport(LOG_SERVER_ONLY,
                                (errhidestmt(true),
                                 errhidecontext(true),
                                 errmsg_internal("Grand total: %zu bytes in %zu blocks; %zu free (%zu chunks); %zu used",
                                                                 grand_totals.totalspace, grand_totals.nblocks,
                                                                 grand_totals.freespace, grand_totals.freechunks,
                                                                 grand_totals.totalspace - grand_totals.freespace)));
        }
}

/*
 * MemoryContextStatsInternal
 *              One recursion level for MemoryContextStats
 *
 * Print stats for this context if possible, but in any case accumulate counts
 * into *totals (if not NULL).
 */
static void
MemoryContextStatsInternal(MemoryContext context, int level,
                                                   int max_level, int max_children,
                                                   MemoryContextCounters *totals,
                                                   bool print_to_stderr)
{
        MemoryContext child;
        int                     ichild;

        Assert(MemoryContextIsValid(context));

        /* Examine the context itself */
        context->methods->stats(context,
                                                        MemoryContextStatsPrint,
                                                        &level,
                                                        totals, print_to_stderr);

        /*
         * Examine children.
         *
         * If we are past the recursion depth limit or already running low on
         * stack, do not print them explicitly but just summarize them. Similarly,
         * if there are more than max_children of them, we do not print the rest
         * explicitly, but just summarize them.
         */
        child = context->firstchild;
        ichild = 0;
        if (level < max_level && !stack_is_too_deep())
        {
                for (; child != NULL && ichild < max_children;
                         child = child->nextchild, ichild++)
                {
                        MemoryContextStatsInternal(child, level + 1,
                                                                           max_level, max_children,
                                                                           totals,
                                                                           print_to_stderr);
                }
        }

        if (child != NULL)
        {
                /* Summarize the rest of the children, avoiding recursion. */
                MemoryContextCounters local_totals;

                memset(&local_totals, 0, sizeof(local_totals));

                ichild = 0;
                while (child != NULL)
                {
                        child->methods->stats(child, NULL, NULL, &local_totals, false);
                        ichild++;
                        child = MemoryContextTraverseNext(child, context);
                }

                if (print_to_stderr)
                {
                        for (int i = 0; i <= level; i++)
                                fprintf(stderr, "  ");
                        fprintf(stderr,
                                        "%d more child contexts containing %zu total in %zu blocks; %zu free (%zu chunks); %zu used\n",
                                        ichild,
                                        local_totals.totalspace,
                                        local_totals.nblocks,
                                        local_totals.freespace,
                                        local_totals.freechunks,
                                        local_totals.totalspace - local_totals.freespace);
                }
                else
                        ereport(LOG_SERVER_ONLY,
                                        (errhidestmt(true),
                                         errhidecontext(true),
                                         errmsg_internal("level: %d; %d more child contexts containing %zu total in %zu blocks; %zu free (%zu chunks); %zu used",
                                                                         level,
                                                                         ichild,
                                                                         local_totals.totalspace,
                                                                         local_totals.nblocks,
                                                                         local_totals.freespace,
                                                                         local_totals.freechunks,
                                                                         local_totals.totalspace - local_totals.freespace)));

                if (totals)
                {
                        totals->nblocks += local_totals.nblocks;
                        totals->freechunks += local_totals.freechunks;
                        totals->totalspace += local_totals.totalspace;
                        totals->freespace += local_totals.freespace;
                }
        }
}

/*
 * MemoryContextStatsPrint
 *              Print callback used by MemoryContextStatsInternal
 *
 * For now, the passthru pointer just points to "int level"; later we might
 * make that more complicated.
 */
static void
MemoryContextStatsPrint(MemoryContext context, void *passthru,
                                                const char *stats_string,
                                                bool print_to_stderr)
{
        int                     level = *(int *) passthru;
        const char *name = context->name;
        const char *ident = context->ident;
        char            truncated_ident[110];
        int                     i;

        /*
         * It seems preferable to label dynahash contexts with just the hash table
         * name.  Those are already unique enough, so the "dynahash" part isn't
         * very helpful, and this way is more consistent with pre-v11 practice.
         */
        if (ident && strcmp(name, "dynahash") == 0)
        {
                name = ident;
                ident = NULL;
        }

        truncated_ident[0] = '\0';

        if (ident)
        {
                /*
                 * Some contexts may have very long identifiers (e.g., SQL queries).
                 * Arbitrarily truncate at 100 bytes, but be careful not to break
                 * multibyte characters.  Also, replace ASCII control characters, such
                 * as newlines, with spaces.
                 */
                int                     idlen = strlen(ident);
                bool            truncated = false;

                strcpy(truncated_ident, ": ");
                i = strlen(truncated_ident);

                if (idlen > 100)
                {
                        idlen = pg_mbcliplen(ident, idlen, 100);
                        truncated = true;
                }

                while (idlen-- > 0)
                {
                        unsigned char c = *ident++;

                        if (c < ' ')
                                c = ' ';
                        truncated_ident[i++] = c;
                }
                truncated_ident[i] = '\0';

                if (truncated)
                        strcat(truncated_ident, "...");
        }

        if (print_to_stderr)
        {
                for (i = 0; i < level; i++)
                        fprintf(stderr, "  ");
                fprintf(stderr, "%s: %s%s\n", name, stats_string, truncated_ident);
        }
        else
                ereport(LOG_SERVER_ONLY,
                                (errhidestmt(true),
                                 errhidecontext(true),
                                 errmsg_internal("level: %d; %s: %s%s",
                                                                 level, name, stats_string, truncated_ident)));
}

/*
 * MemoryContextCheck
 *              Check all chunks in the named context and its children.
 *
 * This is just a debugging utility, so it's not fancy.
 */
#ifdef MEMORY_CONTEXT_CHECKING
void
MemoryContextCheck(MemoryContext context)
{
        Assert(MemoryContextIsValid(context));
        context->methods->check(context);

        for (MemoryContext curr = context->firstchild;
                 curr != NULL;
                 curr = MemoryContextTraverseNext(curr, context))
        {
                Assert(MemoryContextIsValid(curr));
                curr->methods->check(curr);
        }
}
#endif

/*
 * MemoryContextCreate
 *              Context-type-independent part of context creation.
 *
 * This is only intended to be called by context-type-specific
 * context creation routines, not by the unwashed masses.
 *
 * The memory context creation procedure goes like this:
 *      1.  Context-type-specific routine makes some initial space allocation,
 *              including enough space for the context header.  If it fails,
 *              it can ereport() with no damage done.
 *      2.      Context-type-specific routine sets up all type-specific fields of
 *              the header (those beyond MemoryContextData proper), as well as any
 *              other management fields it needs to have a fully valid context.
 *              Usually, failure in this step is impossible, but if it's possible
 *              the initial space allocation should be freed before ereport'ing.
 *      3.      Context-type-specific routine calls MemoryContextCreate() to fill in
 *              the generic header fields and link the context into the context tree.
 *      4.  We return to the context-type-specific routine, which finishes
 *              up type-specific initialization.  This routine can now do things
 *              that might fail (like allocate more memory), so long as it's
 *              sure the node is left in a state that delete will handle.
 *
 * node: the as-yet-uninitialized common part of the context header node.
 * tag: NodeTag code identifying the memory context type.
 * method_id: MemoryContextMethodID of the context-type being created.
 * parent: parent context, or NULL if this will be a top-level context.
 * name: name of context (must be statically allocated).
 *
 * Context routines generally assume that MemoryContextCreate can't fail,
 * so this can contain Assert but not elog/ereport.
 */
void
MemoryContextCreate(MemoryContext node,
                                        NodeTag tag,
                                        MemoryContextMethodID method_id,
                                        MemoryContext parent,
                                        const char *name)
{
        /* Creating new memory contexts is not allowed in a critical section */
        Assert(CritSectionCount == 0);

        /* Initialize all standard fields of memory context header */
        node->type = tag;
        node->isReset = true;
        node->methods = &mcxt_methods[method_id];
        node->parent = parent;
        node->firstchild = NULL;
        node->mem_allocated = 0;
        node->prevchild = NULL;
        node->name = name;
        node->ident = NULL;
        node->reset_cbs = NULL;

        /* OK to link node into context tree */
        if (parent)
        {
                node->nextchild = parent->firstchild;
                if (parent->firstchild != NULL)
                        parent->firstchild->prevchild = node;
                parent->firstchild = node;
                /* inherit allowInCritSection flag from parent */
                node->allowInCritSection = parent->allowInCritSection;
        }
        else
        {
                node->nextchild = NULL;
                node->allowInCritSection = false;
        }

        VALGRIND_CREATE_MEMPOOL(node, 0, false);
}

/*
 * MemoryContextAllocationFailure
 *              For use by MemoryContextMethods implementations to handle when malloc
 *              returns NULL.  The behavior is specific to whether MCXT_ALLOC_NO_OOM
 *              is in 'flags'.
 */
void *
MemoryContextAllocationFailure(MemoryContext context, Size size, int flags)
{
        if ((flags & MCXT_ALLOC_NO_OOM) == 0)
        {
                if (TopMemoryContext)
                        MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }
        return NULL;
}

/*
 * MemoryContextSizeFailure
 *              For use by MemoryContextMethods implementations to handle invalid
 *              memory allocation request sizes.
 */
void
MemoryContextSizeFailure(MemoryContext context, Size size, int flags)
{
        elog(ERROR, "invalid memory alloc request size %zu", size);
}

/*
 * MemoryContextAlloc
 *              Allocate space within the specified context.
 *
 * This could be turned into a macro, but we'd have to import
 * nodes/memnodes.h into postgres.h which seems a bad idea.
 */
void *
MemoryContextAlloc(MemoryContext context, Size size)
{
        void       *ret;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        context->isReset = false;

        /*
         * For efficiency reasons, we purposefully offload the handling of
         * allocation failures to the MemoryContextMethods implementation as this
         * allows these checks to be performed only when an actual malloc needs to
         * be done to request more memory from the OS.  Additionally, not having
         * to execute any instructions after this call allows the compiler to use
         * the sibling call optimization.  If you're considering adding code after
         * this call, consider making it the responsibility of the 'alloc'
         * function instead.
         */
        ret = context->methods->alloc(context, size, 0);

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        return ret;
}

/*
 * MemoryContextAllocZero
 *              Like MemoryContextAlloc, but clears allocated memory
 *
 *      We could just call MemoryContextAlloc then clear the memory, but this
 *      is a very common combination, so we provide the combined operation.
 */
void *
MemoryContextAllocZero(MemoryContext context, Size size)
{
        void       *ret;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        context->isReset = false;

        ret = context->methods->alloc(context, size, 0);

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        MemSetAligned(ret, 0, size);

        return ret;
}

/*
 * MemoryContextAllocExtended
 *              Allocate space within the specified context using the given flags.
 */
void *
MemoryContextAllocExtended(MemoryContext context, Size size, int flags)
{
        void       *ret;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!((flags & MCXT_ALLOC_HUGE) != 0 ? AllocHugeSizeIsValid(size) :
                  AllocSizeIsValid(size)))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size, flags);
        if (unlikely(ret == NULL))
                return NULL;

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        if ((flags & MCXT_ALLOC_ZERO) != 0)
                MemSetAligned(ret, 0, size);

        return ret;
}

/*
 * HandleLogMemoryContextInterrupt
 *              Handle receipt of an interrupt indicating logging of memory
 *              contexts.
 *
 * All the actual work is deferred to ProcessLogMemoryContextInterrupt(),
 * because we cannot safely emit a log message inside the signal handler.
 */
void
HandleLogMemoryContextInterrupt(void)
{
        InterruptPending = true;
        LogMemoryContextPending = true;
        /* latch will be set by procsignal_sigusr1_handler */
}

/*
 * ProcessLogMemoryContextInterrupt
 *              Perform logging of memory contexts of this backend process.
 *
 * Any backend that participates in ProcSignal signaling must arrange
 * to call this function if we see LogMemoryContextPending set.
 * It is called from CHECK_FOR_INTERRUPTS(), which is enough because
 * the target process for logging of memory contexts is a backend.
 */
void
ProcessLogMemoryContextInterrupt(void)
{
        LogMemoryContextPending = false;

        /*
         * Use LOG_SERVER_ONLY to prevent this message from being sent to the
         * connected client.
         */
        ereport(LOG_SERVER_ONLY,
                        (errhidestmt(true),
                         errhidecontext(true),
                         errmsg("logging memory contexts of PID %d", MyProcPid)));

        /*
         * When a backend process is consuming huge memory, logging all its memory
         * contexts might overrun available disk space. To prevent this, we limit
         * the depth of the hierarchy, as well as the number of child contexts to
         * log per parent to 100.
         *
         * As with MemoryContextStats(), we suppose that practical cases where the
         * dump gets long will typically be huge numbers of siblings under the
         * same parent context; while the additional debugging value from seeing
         * details about individual siblings beyond 100 will not be large.
         */
        MemoryContextStatsDetail(TopMemoryContext, 100, 100, false);
}

void *
palloc(Size size)
{
        /* duplicates MemoryContextAlloc to avoid increased overhead */
        void       *ret;
        MemoryContext context = CurrentMemoryContext;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        context->isReset = false;

        /*
         * For efficiency reasons, we purposefully offload the handling of
         * allocation failures to the MemoryContextMethods implementation as this
         * allows these checks to be performed only when an actual malloc needs to
         * be done to request more memory from the OS.  Additionally, not having
         * to execute any instructions after this call allows the compiler to use
         * the sibling call optimization.  If you're considering adding code after
         * this call, consider making it the responsibility of the 'alloc'
         * function instead.
         */
        ret = context->methods->alloc(context, size, 0);
        /* We expect OOM to be handled by the alloc function */
        Assert(ret != NULL);
        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        return ret;
}

void *
palloc0(Size size)
{
        /* duplicates MemoryContextAllocZero to avoid increased overhead */
        void       *ret;
        MemoryContext context = CurrentMemoryContext;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        context->isReset = false;

        ret = context->methods->alloc(context, size, 0);

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        MemSetAligned(ret, 0, size);

        return ret;
}

void *
palloc_extended(Size size, int flags)
{
        /* duplicates MemoryContextAllocExtended to avoid increased overhead */
        void       *ret;
        MemoryContext context = CurrentMemoryContext;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        context->isReset = false;

        ret = context->methods->alloc(context, size, flags);
        if (unlikely(ret == NULL))
        {
                return NULL;
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        if ((flags & MCXT_ALLOC_ZERO) != 0)
                MemSetAligned(ret, 0, size);

        return ret;
}

/*
 * MemoryContextAllocAligned
 *              Allocate 'size' bytes of memory in 'context' aligned to 'alignto'
 *              bytes.
 *
 * Currently, we align addresses by requesting additional bytes from the
 * MemoryContext's standard allocator function and then aligning the returned
 * address by the required alignment.  This means that the given MemoryContext
 * must support providing us with a chunk of memory that's larger than 'size'.
 * For allocators such as Slab, that's not going to work, as slab only allows
 * chunks of the size that's specified when the context is created.
 *
 * 'alignto' must be a power of 2.
 * 'flags' may be 0 or set the same as MemoryContextAllocExtended().
 */
void *
MemoryContextAllocAligned(MemoryContext context,
                                                  Size size, Size alignto, int flags)
{
        MemoryChunk *alignedchunk;
        Size            alloc_size;
        void       *unaligned;
        void       *aligned;

        /* wouldn't make much sense to waste that much space */
        Assert(alignto < (128 * 1024 * 1024));

        /* ensure alignto is a power of 2 */
        Assert((alignto & (alignto - 1)) == 0);

        /*
         * If the alignment requirements are less than what we already guarantee
         * then just use the standard allocation function.
         */
        if (unlikely(alignto <= MAXIMUM_ALIGNOF))
                return MemoryContextAllocExtended(context, size, flags);

        /*
         * We implement aligned pointers by simply allocating enough memory for
         * the requested size plus the alignment and an additional "redirection"
         * MemoryChunk.  This additional MemoryChunk is required for operations
         * such as pfree when used on the pointer returned by this function.  We
         * use this redirection MemoryChunk in order to find the pointer to the
         * memory that was returned by the MemoryContextAllocExtended call below.
         * We do that by "borrowing" the block offset field and instead of using
         * that to find the offset into the owning block, we use it to find the
         * original allocated address.
         *
         * Here we must allocate enough extra memory so that we can still align
         * the pointer returned by MemoryContextAllocExtended and also have enough
         * space for the redirection MemoryChunk.  Since allocations will already
         * be at least aligned by MAXIMUM_ALIGNOF, we can subtract that amount
         * from the allocation size to save a little memory.
         */
        alloc_size = size + PallocAlignedExtraBytes(alignto);

#ifdef MEMORY_CONTEXT_CHECKING
        /* ensure there's space for a sentinel byte */
        alloc_size += 1;
#endif

        /* perform the actual allocation */
        unaligned = MemoryContextAllocExtended(context, alloc_size, flags);

        /* set the aligned pointer */
        aligned = (void *) TYPEALIGN(alignto, (char *) unaligned +
                                                                 sizeof(MemoryChunk));

        alignedchunk = PointerGetMemoryChunk(aligned);

        /*
         * We set the redirect MemoryChunk so that the block offset calculation is
         * used to point back to the 'unaligned' allocated chunk.  This allows us
         * to use MemoryChunkGetBlock() to find the unaligned chunk when we need
         * to perform operations such as pfree() and repalloc().
         *
         * We store 'alignto' in the MemoryChunk's 'value' so that we know what
         * the alignment was set to should we ever be asked to realloc this
         * pointer.
         */
        MemoryChunkSetHdrMask(alignedchunk, unaligned, alignto,
                                                  MCTX_ALIGNED_REDIRECT_ID);

        /* double check we produced a correctly aligned pointer */
        Assert((void *) TYPEALIGN(alignto, aligned) == aligned);

#ifdef MEMORY_CONTEXT_CHECKING
        alignedchunk->requested_size = size;
        /* set mark to catch clobber of "unused" space */
        set_sentinel(aligned, size);
#endif

        /* Mark the bytes before the redirection header as noaccess */
        VALGRIND_MAKE_MEM_NOACCESS(unaligned,
                                                           (char *) alignedchunk - (char *) unaligned);

        /* Disallow access to the redirection chunk header. */
        VALGRIND_MAKE_MEM_NOACCESS(alignedchunk, sizeof(MemoryChunk));

        return aligned;
}

/*
 * palloc_aligned
 *              Allocate 'size' bytes returning a pointer that's aligned to the
 *              'alignto' boundary.
 *
 * Currently, we align addresses by requesting additional bytes from the
 * MemoryContext's standard allocator function and then aligning the returned
 * address by the required alignment.  This means that the given MemoryContext
 * must support providing us with a chunk of memory that's larger than 'size'.
 * For allocators such as Slab, that's not going to work, as slab only allows
 * chunks of the size that's specified when the context is created.
 *
 * 'alignto' must be a power of 2.
 * 'flags' may be 0 or set the same as MemoryContextAllocExtended().
 */
void *
palloc_aligned(Size size, Size alignto, int flags)
{
        return MemoryContextAllocAligned(CurrentMemoryContext, size, alignto, flags);
}

/*
 * pfree
 *              Release an allocated chunk.
 */
void
pfree(void *pointer)
{
#ifdef USE_VALGRIND
        MemoryContextMethodID method = GetMemoryChunkMethodID(pointer);
        MemoryContext context = GetMemoryChunkContext(pointer);
#endif

        MCXT_METHOD(pointer, free_p) (pointer);

#ifdef USE_VALGRIND
        if (method != MCTX_ALIGNED_REDIRECT_ID)
                VALGRIND_MEMPOOL_FREE(context, pointer);
#endif
}

/*
 * repalloc
 *              Adjust the size of a previously allocated chunk.
 */
void *
repalloc(void *pointer, Size size)
{
#ifdef USE_VALGRIND
        MemoryContextMethodID method = GetMemoryChunkMethodID(pointer);
#endif
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
        MemoryContext context = GetMemoryChunkContext(pointer);
#endif
        void       *ret;

        AssertNotInCriticalSection(context);

        /* isReset must be false already */
        Assert(!context->isReset);

        /*
         * For efficiency reasons, we purposefully offload the handling of
         * allocation failures to the MemoryContextMethods implementation as this
         * allows these checks to be performed only when an actual malloc needs to
         * be done to request more memory from the OS.  Additionally, not having
         * to execute any instructions after this call allows the compiler to use
         * the sibling call optimization.  If you're considering adding code after
         * this call, consider making it the responsibility of the 'realloc'
         * function instead.
         */
        ret = MCXT_METHOD(pointer, realloc) (pointer, size, 0);

#ifdef USE_VALGRIND
        if (method != MCTX_ALIGNED_REDIRECT_ID)
                VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
#endif

        return ret;
}

/*
 * repalloc_extended
 *              Adjust the size of a previously allocated chunk,
 *              with HUGE and NO_OOM options.
 */
void *
repalloc_extended(void *pointer, Size size, int flags)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
        MemoryContext context = GetMemoryChunkContext(pointer);
#endif
        void       *ret;

        AssertNotInCriticalSection(context);

        /* isReset must be false already */
        Assert(!context->isReset);

        /*
         * For efficiency reasons, we purposefully offload the handling of
         * allocation failures to the MemoryContextMethods implementation as this
         * allows these checks to be performed only when an actual malloc needs to
         * be done to request more memory from the OS.  Additionally, not having
         * to execute any instructions after this call allows the compiler to use
         * the sibling call optimization.  If you're considering adding code after
         * this call, consider making it the responsibility of the 'realloc'
         * function instead.
         */
        ret = MCXT_METHOD(pointer, realloc) (pointer, size, flags);
        if (unlikely(ret == NULL))
                return NULL;

        VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);

        return ret;
}

/*
 * repalloc0
 *              Adjust the size of a previously allocated chunk and zero out the added
 *              space.
 */
void *
repalloc0(void *pointer, Size oldsize, Size size)
{
        void       *ret;

        /* catch wrong argument order */
        if (unlikely(oldsize > size))
                elog(ERROR, "invalid repalloc0 call: oldsize %zu, new size %zu",
                         oldsize, size);

        ret = repalloc(pointer, size);
        memset((char *) ret + oldsize, 0, (size - oldsize));
        return ret;
}

/*
 * MemoryContextAllocHuge
 *              Allocate (possibly-expansive) space within the specified context.
 *
 * See considerations in comment at MaxAllocHugeSize.
 */
void *
MemoryContextAllocHuge(MemoryContext context, Size size)
{
        void       *ret;

        Assert(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        context->isReset = false;

        /*
         * For efficiency reasons, we purposefully offload the handling of
         * allocation failures to the MemoryContextMethods implementation as this
         * allows these checks to be performed only when an actual malloc needs to
         * be done to request more memory from the OS.  Additionally, not having
         * to execute any instructions after this call allows the compiler to use
         * the sibling call optimization.  If you're considering adding code after
         * this call, consider making it the responsibility of the 'alloc'
         * function instead.
         */
        ret = context->methods->alloc(context, size, MCXT_ALLOC_HUGE);

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        return ret;
}

/*
 * repalloc_huge
 *              Adjust the size of a previously allocated chunk, permitting a large
 *              value.  The previous allocation need not have been "huge".
 */
void *
repalloc_huge(void *pointer, Size size)
{
        /* this one seems not worth its own implementation */
        return repalloc_extended(pointer, size, MCXT_ALLOC_HUGE);
}

/*
 * MemoryContextStrdup
 *              Like strdup(), but allocate from the specified context
 */
char *
MemoryContextStrdup(MemoryContext context, const char *string)
{
        char       *nstr;
        Size            len = strlen(string) + 1;

        nstr = (char *) MemoryContextAlloc(context, len);

        memcpy(nstr, string, len);

        return nstr;
}

char *
pstrdup(const char *in)
{
        return MemoryContextStrdup(CurrentMemoryContext, in);
}

/*
 * pnstrdup
 *              Like pstrdup(), but append null byte to a
 *              not-necessarily-null-terminated input string.
 */
char *
pnstrdup(const char *in, Size len)
{
        char       *out;

        len = strnlen(in, len);

        out = palloc(len + 1);
        memcpy(out, in, len);
        out[len] = '\0';

        return out;
}

/*
 * Make copy of string with all trailing newline characters removed.
 */
char *
pchomp(const char *in)
{
        size_t          n;

        n = strlen(in);
        while (n > 0 && in[n - 1] == '\n')
                n--;
        return pnstrdup(in, n);
}