gio/kqueue/kqueue-utils.c

   1 /*******************************************************************************
   2   Copyright (c) 2011, 2012 Dmitry Matveev <me@dmitrymatveev.co.uk>
   3
   4   Permission is hereby granted, free of charge, to any person obtaining a copy
   5   of this software and associated documentation files (the "Software"), to deal
   6   in the Software without restriction, including without limitation the rights
   7   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8   copies of the Software, and to permit persons to whom the Software is
   9   furnished to do so, subject to the following conditions:
  10
  11   The above copyright notice and this permission notice shall be included in
  12   all copies or substantial portions of the Software.
  13
  14   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  20   THE SOFTWARE.
  21 *******************************************************************************/
  22
  23 #include <sys/types.h>
  24 #include <sys/event.h>
  25 #include <string.h>
  26 #include <glib.h>
  27 #include <unistd.h>
  28 #include <sys/stat.h>
  29 #include <errno.h>
  30 #include "kqueue-utils.h"
  31
  32 static gboolean ku_debug_enabled = FALSE;
  33 #define KU_W if (ku_debug_enabled) g_warning
  34
  35
  36
  37 #define KEVENTS_EXTEND_COUNT 10
  38
  39
  40 /**
  41  * kevents_init_sz:
  42  * @kv: a #kevents
  43  * @n_initial: the initial preallocated memory size. If it is less than
  44  *      %KEVENTS_EXTEND_COUNT, this value will be used instead.
  45  *
  46  * Initializes a #kevents object.
  47  **/
  48 void
  49 kevents_init_sz (kevents *kv, gsize n_initial)
  50 {
  51   g_assert (kv != NULL);
  52
  53   memset (kv, 0, sizeof (kevents));
  54
  55   if (n_initial < KEVENTS_EXTEND_COUNT)
  56     n_initial = KEVENTS_EXTEND_COUNT;
  57
  58   kv->memory = g_new0 (struct kevent, n_initial);
  59   kv->kq_allocated = n_initial;
  60 }
  61
  62
  63 /**
  64  * kevents_extend_sz:
  65  * @kv: a #kevents
  66  * @n_new: the number of new objects to be added
  67  *
  68  * Extends the allocated memory, if needed.
  69  **/
  70 void
  71 kevents_extend_sz (kevents *kv, gsize n_new)
  72 {
  73   g_assert (kv != NULL);
  74
  75   if (kv->kq_size + n_new <= kv->kq_allocated)
  76     return;
  77
  78   kv->kq_allocated += (n_new + KEVENTS_EXTEND_COUNT);
  79   kv->memory = g_renew (struct kevent, kv->memory, kv->kq_allocated);
  80 }
  81
  82
  83 /**
  84  * kevents_reduce:
  85  * @kv: a #kevents
  86  *
  87  * Reduces the allocated heap size, if needed.
  88  *
  89  * If the allocated heap size is >= 3*used
  90  * and 2*used >= %KEVENTS_EXTEND_COUNT, reduce it to 2*used.
  91  **/
  92 void
  93 kevents_reduce (kevents *kv)
  94 {
  95   g_assert (kv != NULL);
  96   gsize candidate_sz;
  97
  98   if (kv->kq_size == 0 || kv->kq_allocated == 0 || kv->memory == NULL)
  99     return;
 100
 101   candidate_sz = 2 * kv->kq_size;
 102
 103   if (((double) kv->kq_allocated / kv->kq_size) >= 3 &&
 104       candidate_sz >= KEVENTS_EXTEND_COUNT)
 105     {
 106       kv->kq_allocated = candidate_sz;
 107       kv->memory = g_renew (struct kevent, kv->memory, kv->kq_allocated);
 108     }
 109 }
 110
 111
 112 /**
 113  * kevents_free:
 114  * @kv: a #kevents
 115  *
 116  * Resets the kevents object and frees all the associated memory.
 117  **/
 118 void
 119 kevents_free (kevents *kv)
 120 {
 121   g_assert (kv != NULL);
 122
 123   g_free (kv->memory);
 124   memset (kv, 0, sizeof (kevents));
 125 }
 126
 127
 128 #define SAFE_GENERIC_OP(fcn, fd, data, size) \
 129   while (size > 0) \
 130     { \
 131       gsize retval = fcn (fd, data, size); \
 132       if (retval == -1) \
 133         { \
 134           if (errno == EINTR) \
 135             continue; \
 136           else \
 137             return FALSE; \
 138         } \
 139       size -= retval; \
 140       data += retval; \
 141     } \
 142   return TRUE;
 143
 144
 145 /**
 146  * _ku_read:
 147  * @fd: a file descriptor
 148  * @data: the destination buffer
 149  * @size: how many bytes to read
 150  *
 151  * A ready-to-EINTR version of read().
 152  *
 153  * This function expects to work with a blocking socket.
 154  *
 155  * Returns: %TRUE on success, %FALSE otherwise
 156  **/
 157 gboolean
 158 _ku_read (int fd, gpointer data, gsize size)
 159 {
 160   SAFE_GENERIC_OP (read, fd, data, size);
 161 }
 162
 163
 164 /**
 165  * _ku_write:
 166  * @fd: a file descriptor
 167  * @data: the buffer to write
 168  * @size: how many bytes to write
 169  *
 170  * A ready-to-EINTR version of write().
 171  *
 172  * This function expects to work with a blocking socket.
 173  *
 174  * Returns: %TRUE on success, %FALSE otherwise
 175  **/
 176 gboolean
 177 _ku_write (int fd, gconstpointer data, gsize size)
 178 {
 179   SAFE_GENERIC_OP (write, fd, data, size);
 180 }
 181
 182
 183 /**
 184  * Get some file information by its file descriptor.
 185  *
 186  * @param[in]  fd      A file descriptor.
 187  * @param[out] is_dir  A flag indicating directory.
 188  * @param[out] inode   A file's inode number.
 189  **/
 190 void
 191 _ku_file_information (int fd, int *is_dir, ino_t *inode)
 192 {
 193   g_assert (fd != -1);
 194
 195   struct stat st;
 196   memset (&st, 0, sizeof (struct stat));
 197
 198   if (fstat (fd, &st) == -1)
 199     {
 200       KU_W ("fstat failed, assuming it is just a file");
 201       is_dir = NULL;
 202       return;
 203     }
 204
 205   if (is_dir != NULL)
 206       *is_dir = ((st.st_mode & S_IFDIR) == S_IFDIR) ? 1 : 0;
 207
 208   if (inode != NULL)
 209       *inode = st.st_ino;
 210 }