/*

 ** 2008 Jan 22

 **

 ** The author disclaims copyright to this source code.  In place of

 ** a legal notice, here is a blessing:

 **

 **    May you do good and not evil.

 **    May you find forgiveness for yourself and forgive others.

 **    May you share freely, never taking more than you give.

 **

 *************************************************************************

 **

 ** $Id: fault.c,v 1.11 2008/09/02 00:52:52 drh Exp $

 */

 /*

 ** This file contains code to support the concept of "benign" 

 ** malloc failures (when the xMalloc() or xRealloc() method of the

 ** sqlite3_mem_methods structure fails to allocate a block of memory

 ** and returns 0). 

 **

 ** Most malloc failures are non-benign. After they occur, SQLite

 ** abandons the current operation and returns an error code (usually

 ** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily

 ** fatal. For example, if a malloc fails while resizing a hash table, this 

 ** is completely recoverable simply by not carrying out the resize. The 

 ** hash table will continue to function normally.  So a malloc failure 

 ** during a hash table resize is a benign fault.

 */

 #include "sqliteInt.h"

 #ifndef SQLITE_OMIT_BUILTIN_TEST

 /*

 ** Global variables.

 */

 typedef struct BenignMallocHooks BenignMallocHooks;

 static SQLITE_WSD struct BenignMallocHooks {

   void (*xBenignBegin)(void);

   void (*xBenignEnd)(void);

 } sqlite3Hooks = { 0, 0 };

 /* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks

 ** structure.  If writable static data is unsupported on the target,

 ** we have to locate the state vector at run-time.  In the more common

 ** case where writable static data is supported, wsdHooks can refer directly

 ** to the "sqlite3Hooks" state vector declared above.

 */

 #ifdef SQLITE_OMIT_WSD

 # define wsdHooksInit \

   BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)

 # define wsdHooks x[0]

 #else

 # define wsdHooksInit

 # define wsdHooks sqlite3Hooks

 #endif

 /*

 ** Register hooks to call when sqlite3BeginBenignMalloc() and

 ** sqlite3EndBenignMalloc() are called, respectively.

 */

 void sqlite3BenignMallocHooks(

   void (*xBenignBegin)(void),

   void (*xBenignEnd)(void)

 ){

   wsdHooksInit;

   wsdHooks.xBenignBegin = xBenignBegin;

   wsdHooks.xBenignEnd = xBenignEnd;

 }

 /*

 ** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that

 ** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()

 ** indicates that subsequent malloc failures are non-benign.

 */

 void sqlite3BeginBenignMalloc(void){

   wsdHooksInit;

   if( wsdHooks.xBenignBegin ){

     wsdHooks.xBenignBegin();

   }

 }

 void sqlite3EndBenignMalloc(void){

   wsdHooksInit;

   if( wsdHooks.xBenignEnd ){

     wsdHooks.xBenignEnd();

   }

 }

 #endif   /* #ifndef SQLITE_OMIT_BUILTIN_TEST */