AryaWu/sqlite

1/*2** 2008 Jan 223**4** The author disclaims copyright to this source code.  In place of5** a legal notice, here is a blessing:6**7**    May you do good and not evil.8**    May you find forgiveness for yourself and forgive others.9**    May you share freely, never taking more than you give.10**11*************************************************************************12**13** This file contains code to support the concept of "benign" 14** malloc failures (when the xMalloc() or xRealloc() method of the15** sqlite3_mem_methods structure fails to allocate a block of memory16** and returns 0). 17**18** Most malloc failures are non-benign. After they occur, SQLite19** abandons the current operation and returns an error code (usually20** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily21** fatal. For example, if a malloc fails while resizing a hash table, this 22** is completely recoverable simply by not carrying out the resize. The 23** hash table will continue to function normally.  So a malloc failure 24** during a hash table resize is a benign fault.25*/26 27#include "sqliteInt.h"28 29#ifndef SQLITE_UNTESTABLE30 31/*32** Global variables.33*/34typedef struct BenignMallocHooks BenignMallocHooks;35static SQLITE_WSD struct BenignMallocHooks {36  void (*xBenignBegin)(void);37  void (*xBenignEnd)(void);38} sqlite3Hooks = { 0, 0 };39 40/* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks41** structure.  If writable static data is unsupported on the target,42** we have to locate the state vector at run-time.  In the more common43** case where writable static data is supported, wsdHooks can refer directly44** to the "sqlite3Hooks" state vector declared above.45*/46#ifdef SQLITE_OMIT_WSD47# define wsdHooksInit \48  BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)49# define wsdHooks x[0]50#else51# define wsdHooksInit52# define wsdHooks sqlite3Hooks53#endif54 55 56/*57** Register hooks to call when sqlite3BeginBenignMalloc() and58** sqlite3EndBenignMalloc() are called, respectively.59*/60void sqlite3BenignMallocHooks(61  void (*xBenignBegin)(void),62  void (*xBenignEnd)(void)63){64  wsdHooksInit;65  wsdHooks.xBenignBegin = xBenignBegin;66  wsdHooks.xBenignEnd = xBenignEnd;67}68 69/*70** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that71** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()72** indicates that subsequent malloc failures are non-benign.73*/74void sqlite3BeginBenignMalloc(void){75  wsdHooksInit;76  if( wsdHooks.xBenignBegin ){77    wsdHooks.xBenignBegin();78  }79}80void sqlite3EndBenignMalloc(void){81  wsdHooksInit;82  if( wsdHooks.xBenignEnd ){83    wsdHooks.xBenignEnd();84  }85}86 87#endif   /* #ifndef SQLITE_UNTESTABLE */88