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sqlite3

    1: /*
    2: ** 2008 Jan 22
    3: **
    4: ** The author disclaims copyright to this source code.  In place of
    5: ** 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 the
   15: ** sqlite3_mem_methods structure fails to allocate a block of memory
   16: ** and returns 0). 
   17: **
   18: ** Most malloc failures are non-benign. After they occur, SQLite
   19: ** abandons the current operation and returns an error code (usually
   20: ** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
   21: ** 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_OMIT_BUILTIN_TEST
   30: 
   31: /*
   32: ** Global variables.
   33: */
   34: typedef struct BenignMallocHooks BenignMallocHooks;
   35: static 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 BenignMallocHooks
   41: ** structure.  If writable static data is unsupported on the target,
   42: ** we have to locate the state vector at run-time.  In the more common
   43: ** case where writable static data is supported, wsdHooks can refer directly
   44: ** to the "sqlite3Hooks" state vector declared above.
   45: */
   46: #ifdef SQLITE_OMIT_WSD
   47: # define wsdHooksInit \
   48:   BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)
   49: # define wsdHooks x[0]
   50: #else
   51: # define wsdHooksInit
   52: # define wsdHooks sqlite3Hooks
   53: #endif
   54: 
   55: 
   56: /*
   57: ** Register hooks to call when sqlite3BeginBenignMalloc() and
   58: ** sqlite3EndBenignMalloc() are called, respectively.
   59: */
   60: void 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 that
   71: ** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()
   72: ** indicates that subsequent malloc failures are non-benign.
   73: */
   74: void sqlite3BeginBenignMalloc(void){
   75:   wsdHooksInit;
   76:   if( wsdHooks.xBenignBegin ){
   77:     wsdHooks.xBenignBegin();
   78:   }
   79: }
   80: void sqlite3EndBenignMalloc(void){
   81:   wsdHooksInit;
   82:   if( wsdHooks.xBenignEnd ){
   83:     wsdHooks.xBenignEnd();
   84:   }
   85: }
   86: 
   87: #endif   /* #ifndef SQLITE_OMIT_BUILTIN_TEST */