/*

** 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 */