content/common/host_discardable_shared_memory_manager.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/common/host_discardable_shared_memory_manager.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/atomic_sequence_num.h"
  10 #include "base/bind.h"
  11 #include "base/callback.h"
  12 #include "base/debug/crash_logging.h"
  13 #include "base/lazy_instance.h"
  14 #include "base/memory/discardable_memory.h"
  15 #include "base/numerics/safe_math.h"
  16 #include "base/strings/string_number_conversions.h"
  17 #include "base/strings/stringprintf.h"
  18 #include "base/sys_info.h"
  19 #include "base/thread_task_runner_handle.h"
  20 #include "base/trace_event/memory_allocator_dump.h"
  21 #include "base/trace_event/memory_dump_manager.h"
  22 #include "base/trace_event/process_memory_dump.h"
  23 #include "base/trace_event/trace_event.h"
  24 #include "content/common/child_process_host_impl.h"
  25 #include "content/common/discardable_shared_memory_heap.h"
  26 #include "content/public/common/child_process_host.h"
  27
  28 namespace content {
  29 namespace {
  30
  31 class DiscardableMemoryImpl : public base::DiscardableMemory {
  32  public:
  33   DiscardableMemoryImpl(scoped_ptr<base::DiscardableSharedMemory> shared_memory,
  34                         const base::Closure& deleted_callback)
  35       : shared_memory_(shared_memory.Pass()),
  36         deleted_callback_(deleted_callback),
  37         is_locked_(true) {}
  38
  39   ~DiscardableMemoryImpl() override {
  40     if (is_locked_)
  41       shared_memory_->Unlock(0, 0);
  42
  43     deleted_callback_.Run();
  44   }
  45
  46   // Overridden from base::DiscardableMemory:
  47   bool Lock() override {
  48     DCHECK(!is_locked_);
  49
  50     if (shared_memory_->Lock(0, 0) != base::DiscardableSharedMemory::SUCCESS)
  51       return false;
  52
  53     is_locked_ = true;
  54     return true;
  55   }
  56   void Unlock() override {
  57     DCHECK(is_locked_);
  58
  59     shared_memory_->Unlock(0, 0);
  60     is_locked_ = false;
  61   }
  62   void* data() const override {
  63     DCHECK(is_locked_);
  64     return shared_memory_->memory();
  65   }
  66
  67  private:
  68   scoped_ptr<base::DiscardableSharedMemory> shared_memory_;
  69   const base::Closure deleted_callback_;
  70   bool is_locked_;
  71
  72   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryImpl);
  73 };
  74
  75 base::LazyInstance<HostDiscardableSharedMemoryManager>
  76     g_discardable_shared_memory_manager = LAZY_INSTANCE_INITIALIZER;
  77
  78 #if defined(OS_ANDROID)
  79 // Limits the number of FDs used to 32, assuming a 4MB allocation size.
  80 const int64_t kMaxDefaultMemoryLimit = 128 * 1024 * 1024;
  81 #else
  82 const int64_t kMaxDefaultMemoryLimit = 512 * 1024 * 1024;
  83 #endif
  84
  85 const int kEnforceMemoryPolicyDelayMs = 1000;
  86
  87 // Global atomic to generate unique discardable shared memory IDs.
  88 base::StaticAtomicSequenceNumber g_next_discardable_shared_memory_id;
  89
  90 }  // namespace
  91
  92 HostDiscardableSharedMemoryManager::MemorySegment::MemorySegment(
  93     scoped_ptr<base::DiscardableSharedMemory> memory)
  94     : memory_(memory.Pass()) {
  95 }
  96
  97 HostDiscardableSharedMemoryManager::MemorySegment::~MemorySegment() {
  98 }
  99
 100 HostDiscardableSharedMemoryManager::HostDiscardableSharedMemoryManager()
 101     : memory_limit_(
 102           // Allow 25% of physical memory to be used for discardable memory.
 103           std::min(base::SysInfo::AmountOfPhysicalMemory() / 4,
 104                    base::SysInfo::IsLowEndDevice()
 105                        ?
 106                        // Use 1/8th of discardable memory on low-end devices.
 107                        kMaxDefaultMemoryLimit / 8
 108                        : kMaxDefaultMemoryLimit)),
 109       bytes_allocated_(0),
 110       memory_pressure_listener_(new base::MemoryPressureListener(
 111           base::Bind(&HostDiscardableSharedMemoryManager::OnMemoryPressure,
 112                      base::Unretained(this)))),
 113       enforce_memory_policy_pending_(false),
 114       weak_ptr_factory_(this) {
 115   DCHECK_NE(memory_limit_, 0u);
 116   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
 117       this);
 118 }
 119
 120 HostDiscardableSharedMemoryManager::~HostDiscardableSharedMemoryManager() {
 121   base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
 122       this);
 123 }
 124
 125 HostDiscardableSharedMemoryManager*
 126 HostDiscardableSharedMemoryManager::current() {
 127   return g_discardable_shared_memory_manager.Pointer();
 128 }
 129
 130 scoped_ptr<base::DiscardableMemory>
 131 HostDiscardableSharedMemoryManager::AllocateLockedDiscardableMemory(
 132     size_t size) {
 133   DiscardableSharedMemoryId new_id =
 134       g_next_discardable_shared_memory_id.GetNext();
 135   base::ProcessHandle current_process_handle = base::GetCurrentProcessHandle();
 136
 137   // Note: Use DiscardableSharedMemoryHeap for in-process allocation
 138   // of discardable memory if the cost of each allocation is too high.
 139   base::SharedMemoryHandle handle;
 140   AllocateLockedDiscardableSharedMemory(current_process_handle,
 141                                         ChildProcessHost::kInvalidUniqueID,
 142                                         size, new_id, &handle);
 143   CHECK(base::SharedMemory::IsHandleValid(handle));
 144   scoped_ptr<base::DiscardableSharedMemory> memory(
 145       new base::DiscardableSharedMemory(handle));
 146   CHECK(memory->Map(size));
 147   // Close file descriptor to avoid running out.
 148   memory->Close();
 149   return make_scoped_ptr(new DiscardableMemoryImpl(
 150       memory.Pass(),
 151       base::Bind(
 152           &HostDiscardableSharedMemoryManager::DeletedDiscardableSharedMemory,
 153           base::Unretained(this), new_id, ChildProcessHost::kInvalidUniqueID)));
 154 }
 155
 156 bool HostDiscardableSharedMemoryManager::OnMemoryDump(
 157     const base::trace_event::MemoryDumpArgs& args,
 158     base::trace_event::ProcessMemoryDump* pmd) {
 159   base::AutoLock lock(lock_);
 160   for (const auto& process_entry : processes_) {
 161     const int child_process_id = process_entry.first;
 162     const MemorySegmentMap& process_segments = process_entry.second;
 163     for (const auto& segment_entry : process_segments) {
 164       const int segment_id = segment_entry.first;
 165       const MemorySegment* segment = segment_entry.second.get();
 166       std::string dump_name = base::StringPrintf(
 167           "discardable/process_%x/segment_%d", child_process_id, segment_id);
 168       base::trace_event::MemoryAllocatorDump* dump =
 169           pmd->CreateAllocatorDump(dump_name);
 170       dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
 171                       base::trace_event::MemoryAllocatorDump::kUnitsBytes,
 172                       segment->memory()->mapped_size());
 173
 174       // Create the cross-process ownership edge. If the child creates a
 175       // corresponding dump for the same segment, this will avoid to
 176       // double-count them in tracing. If, instead, no other process will emit a
 177       // dump with the same guid, the segment will be accounted to the browser.
 178       const uint64 child_tracing_process_id =
 179           ChildProcessHostImpl::ChildProcessUniqueIdToTracingProcessId(
 180               child_process_id);
 181       base::trace_event::MemoryAllocatorDumpGuid shared_segment_guid =
 182           DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(
 183               child_tracing_process_id, segment_id);
 184       pmd->CreateSharedGlobalAllocatorDump(shared_segment_guid);
 185       pmd->AddOwnershipEdge(dump->guid(), shared_segment_guid);
 186     }
 187   }
 188   return true;
 189 }
 190
 191 void HostDiscardableSharedMemoryManager::
 192     AllocateLockedDiscardableSharedMemoryForChild(
 193         base::ProcessHandle process_handle,
 194         int child_process_id,
 195         size_t size,
 196         DiscardableSharedMemoryId id,
 197         base::SharedMemoryHandle* shared_memory_handle) {
 198   AllocateLockedDiscardableSharedMemory(process_handle, child_process_id, size,
 199                                         id, shared_memory_handle);
 200 }
 201
 202 void HostDiscardableSharedMemoryManager::ChildDeletedDiscardableSharedMemory(
 203     DiscardableSharedMemoryId id,
 204     int child_process_id) {
 205   DeletedDiscardableSharedMemory(id, child_process_id);
 206 }
 207
 208 void HostDiscardableSharedMemoryManager::ProcessRemoved(int child_process_id) {
 209   base::AutoLock lock(lock_);
 210
 211   ProcessMap::iterator process_it = processes_.find(child_process_id);
 212   if (process_it == processes_.end())
 213     return;
 214
 215   size_t bytes_allocated_before_releasing_memory = bytes_allocated_;
 216
 217   for (auto& segment_it : process_it->second)
 218     ReleaseMemory(segment_it.second->memory());
 219
 220   processes_.erase(process_it);
 221
 222   if (bytes_allocated_ != bytes_allocated_before_releasing_memory)
 223     BytesAllocatedChanged(bytes_allocated_);
 224 }
 225
 226 void HostDiscardableSharedMemoryManager::SetMemoryLimit(size_t limit) {
 227   base::AutoLock lock(lock_);
 228
 229   memory_limit_ = limit;
 230   ReduceMemoryUsageUntilWithinMemoryLimit();
 231 }
 232
 233 void HostDiscardableSharedMemoryManager::EnforceMemoryPolicy() {
 234   base::AutoLock lock(lock_);
 235
 236   enforce_memory_policy_pending_ = false;
 237   ReduceMemoryUsageUntilWithinMemoryLimit();
 238 }
 239
 240 size_t HostDiscardableSharedMemoryManager::GetBytesAllocated() {
 241   base::AutoLock lock(lock_);
 242
 243   return bytes_allocated_;
 244 }
 245
 246 void HostDiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemory(
 247     base::ProcessHandle process_handle,
 248     int client_process_id,
 249     size_t size,
 250     DiscardableSharedMemoryId id,
 251     base::SharedMemoryHandle* shared_memory_handle) {
 252   base::AutoLock lock(lock_);
 253
 254   // Make sure |id| is not already in use.
 255   MemorySegmentMap& process_segments = processes_[client_process_id];
 256   if (process_segments.find(id) != process_segments.end()) {
 257     LOG(ERROR) << "Invalid discardable shared memory ID";
 258     *shared_memory_handle = base::SharedMemory::NULLHandle();
 259     return;
 260   }
 261
 262   // Memory usage must be reduced to prevent the addition of |size| from
 263   // taking usage above the limit. Usage should be reduced to 0 in cases
 264   // where |size| is greater than the limit.
 265   size_t limit = 0;
 266   // Note: the actual mapped size can be larger than requested and cause
 267   // |bytes_allocated_| to temporarily be larger than |memory_limit_|. The
 268   // error is minimized by incrementing |bytes_allocated_| with the actual
 269   // mapped size rather than |size| below.
 270   if (size < memory_limit_)
 271     limit = memory_limit_ - size;
 272
 273   if (bytes_allocated_ > limit)
 274     ReduceMemoryUsageUntilWithinLimit(limit);
 275
 276   scoped_ptr<base::DiscardableSharedMemory> memory(
 277       new base::DiscardableSharedMemory);
 278   if (!memory->CreateAndMap(size)) {
 279     *shared_memory_handle = base::SharedMemory::NULLHandle();
 280     return;
 281   }
 282
 283   if (!memory->ShareToProcess(process_handle, shared_memory_handle)) {
 284     LOG(ERROR) << "Cannot share discardable memory segment";
 285     *shared_memory_handle = base::SharedMemory::NULLHandle();
 286     return;
 287   }
 288
 289   base::CheckedNumeric<size_t> checked_bytes_allocated = bytes_allocated_;
 290   checked_bytes_allocated += memory->mapped_size();
 291   if (!checked_bytes_allocated.IsValid()) {
 292     *shared_memory_handle = base::SharedMemory::NULLHandle();
 293     return;
 294   }
 295
 296   bytes_allocated_ = checked_bytes_allocated.ValueOrDie();
 297   BytesAllocatedChanged(bytes_allocated_);
 298
 299 #if !defined(DISCARDABLE_SHARED_MEMORY_SHRINKING)
 300   // Close file descriptor to avoid running out.
 301   memory->Close();
 302 #endif
 303
 304   scoped_refptr<MemorySegment> segment(new MemorySegment(memory.Pass()));
 305   process_segments[id] = segment.get();
 306   segments_.push_back(segment.get());
 307   std::push_heap(segments_.begin(), segments_.end(), CompareMemoryUsageTime);
 308
 309   if (bytes_allocated_ > memory_limit_)
 310     ScheduleEnforceMemoryPolicy();
 311 }
 312
 313 void HostDiscardableSharedMemoryManager::DeletedDiscardableSharedMemory(
 314     DiscardableSharedMemoryId id,
 315     int client_process_id) {
 316   base::AutoLock lock(lock_);
 317
 318   MemorySegmentMap& process_segments = processes_[client_process_id];
 319
 320   MemorySegmentMap::iterator segment_it = process_segments.find(id);
 321   if (segment_it == process_segments.end()) {
 322     LOG(ERROR) << "Invalid discardable shared memory ID";
 323     return;
 324   }
 325
 326   size_t bytes_allocated_before_releasing_memory = bytes_allocated_;
 327
 328   ReleaseMemory(segment_it->second->memory());
 329
 330   process_segments.erase(segment_it);
 331
 332   if (bytes_allocated_ != bytes_allocated_before_releasing_memory)
 333     BytesAllocatedChanged(bytes_allocated_);
 334 }
 335
 336 void HostDiscardableSharedMemoryManager::OnMemoryPressure(
 337     base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
 338   base::AutoLock lock(lock_);
 339
 340   switch (memory_pressure_level) {
 341     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
 342       break;
 343     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
 344       // Purge memory until usage is within half of |memory_limit_|.
 345       ReduceMemoryUsageUntilWithinLimit(memory_limit_ / 2);
 346       break;
 347     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
 348       // Purge everything possible when pressure is critical.
 349       ReduceMemoryUsageUntilWithinLimit(0);
 350       break;
 351   }
 352 }
 353
 354 void
 355 HostDiscardableSharedMemoryManager::ReduceMemoryUsageUntilWithinMemoryLimit() {
 356   lock_.AssertAcquired();
 357
 358   if (bytes_allocated_ <= memory_limit_)
 359     return;
 360
 361   ReduceMemoryUsageUntilWithinLimit(memory_limit_);
 362   if (bytes_allocated_ > memory_limit_)
 363     ScheduleEnforceMemoryPolicy();
 364 }
 365
 366 void HostDiscardableSharedMemoryManager::ReduceMemoryUsageUntilWithinLimit(
 367     size_t limit) {
 368   TRACE_EVENT1("renderer_host",
 369                "HostDiscardableSharedMemoryManager::"
 370                "ReduceMemoryUsageUntilWithinLimit",
 371                "bytes_allocated",
 372                bytes_allocated_);
 373
 374   // Usage time of currently locked segments are updated to this time and
 375   // we stop eviction attempts as soon as we come across a segment that we've
 376   // previously tried to evict but was locked.
 377   base::Time current_time = Now();
 378
 379   lock_.AssertAcquired();
 380   size_t bytes_allocated_before_purging = bytes_allocated_;
 381   while (!segments_.empty()) {
 382     if (bytes_allocated_ <= limit)
 383       break;
 384
 385     // Stop eviction attempts when the LRU segment is currently in use.
 386     if (segments_.front()->memory()->last_known_usage() >= current_time)
 387       break;
 388
 389     std::pop_heap(segments_.begin(), segments_.end(), CompareMemoryUsageTime);
 390     scoped_refptr<MemorySegment> segment = segments_.back();
 391     segments_.pop_back();
 392
 393     // Attempt to purge LRU segment. When successful, released the memory.
 394     if (segment->memory()->Purge(current_time)) {
 395 #if defined(DISCARDABLE_SHARED_MEMORY_SHRINKING)
 396       size_t size = segment->memory()->mapped_size();
 397       DCHECK_GE(bytes_allocated_, size);
 398       bytes_allocated_ -= size;
 399       // Shrink memory segment. This will immediately release the memory to
 400       // the OS.
 401       segment->memory()->Shrink();
 402       DCHECK_EQ(segment->memory()->mapped_size(), 0u);
 403 #endif
 404       ReleaseMemory(segment->memory());
 405       continue;
 406     }
 407
 408     // Add memory segment (with updated usage timestamp) back on heap after
 409     // failed attempt to purge it.
 410     segments_.push_back(segment.get());
 411     std::push_heap(segments_.begin(), segments_.end(), CompareMemoryUsageTime);
 412   }
 413
 414   if (bytes_allocated_ != bytes_allocated_before_purging)
 415     BytesAllocatedChanged(bytes_allocated_);
 416 }
 417
 418 void HostDiscardableSharedMemoryManager::ReleaseMemory(
 419     base::DiscardableSharedMemory* memory) {
 420   lock_.AssertAcquired();
 421
 422   size_t size = memory->mapped_size();
 423   DCHECK_GE(bytes_allocated_, size);
 424   bytes_allocated_ -= size;
 425
 426   // This will unmap the memory segment and drop our reference. The result
 427   // is that the memory will be released to the OS if the child process is
 428   // no longer referencing it.
 429   // Note: We intentionally leave the segment in the |segments| vector to
 430   // avoid reconstructing the heap. The element will be removed from the heap
 431   // when its last usage time is older than all other segments.
 432   memory->Unmap();
 433   memory->Close();
 434 }
 435
 436 void HostDiscardableSharedMemoryManager::BytesAllocatedChanged(
 437     size_t new_bytes_allocated) const {
 438   TRACE_COUNTER1("renderer_host", "TotalDiscardableMemoryUsage",
 439                  new_bytes_allocated);
 440
 441   static const char kTotalDiscardableMemoryAllocatedKey[] =
 442       "total-discardable-memory-allocated";
 443   base::debug::SetCrashKeyValue(kTotalDiscardableMemoryAllocatedKey,
 444                                 base::Uint64ToString(new_bytes_allocated));
 445 }
 446
 447 base::Time HostDiscardableSharedMemoryManager::Now() const {
 448   return base::Time::Now();
 449 }
 450
 451 void HostDiscardableSharedMemoryManager::ScheduleEnforceMemoryPolicy() {
 452   lock_.AssertAcquired();
 453
 454   if (enforce_memory_policy_pending_)
 455     return;
 456
 457   enforce_memory_policy_pending_ = true;
 458   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
 459       FROM_HERE,
 460       base::Bind(&HostDiscardableSharedMemoryManager::EnforceMemoryPolicy,
 461                  weak_ptr_factory_.GetWeakPtr()),
 462       base::TimeDelta::FromMilliseconds(kEnforceMemoryPolicyDelayMs));
 463 }
 464
 465 }  // namespace content