/**
* threads.c: set of generic threading related routines
*
* See Copyright for the status of this software.
*
* Gary Pennington <Gary.Pennington@uk.sun.com>
* daniel@veillard.com
*/
#define IN_LIBXML
#include "XmlEnglibxml.h"
#include <string.h>
//#include "Libxml2_threads.h"
#include "Libxml2_globals.h"
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_PTHREAD_H
#include <pthread.h>
#endif
/* #define DEBUG_THREADS */
/*
* TODO: this module still uses malloc/free and not xmlMalloc/xmlFree
* to avoid some crazyness since xmlMalloc/xmlFree may actually
* be hosted on allocated blocks needing them for the allocation ...
*/
/*
* xmlMutex are a simple mutual exception locks
*/
struct _xmlMutex {
#ifdef HAVE_PTHREAD_H
pthread_mutex_t lock;
#else
int empty;
#endif
};
/*
* xmlRMutex are reentrant mutual exception locks
*/
struct _xmlRMutex {
#ifdef HAVE_PTHREAD_H
pthread_mutex_t lock;
unsigned int held;
unsigned int waiters;
pthread_t tid;
pthread_cond_t cv;
#else
int empty;
#endif
};
/*
* This module still has some internal static data.
* - xmlLibraryLock a global lock
* - globalkey used for per-thread data
*/
#ifdef HAVE_PTHREAD_H
static pthread_key_t globalkey;
static pthread_t mainthread;
static pthread_once_t once_control = PTHREAD_ONCE_INIT;
//xmlGlobalStatePtr gs = NULL;
#endif
#ifdef LIBXML_THREAD_ENABLED
static void xmlOnceInit(void);
#endif
/**
* xmlNewMutex:
*
* xmlNewMutex() is used to allocate a libxml2 token struct for use in
* synchronizing access to data.
*
* Returns a new simple mutex pointer or NULL in case of error
*
* OOM: possible --> NULL is returned (OOM flag is NOT SET)
*/
xmlMutexPtr
xmlNewMutex(void)
{
xmlMutexPtr tok;
if ((tok = (xmlMutexPtr)malloc(sizeof(xmlMutex))) == NULL)
return (NULL);
#ifdef HAVE_PTHREAD_H
pthread_mutex_init(&tok->lock, NULL);
#endif
return (tok);
}
/**
* xmlFreeMutex:
* @tok: the simple mutex
*
* xmlFreeMutex() is used to reclaim resources associated with a libxml2 token
* struct.
*/
void
xmlFreeMutex(xmlMutexPtr tok)
{
if (tok == NULL) return;
#ifdef HAVE_PTHREAD_H
pthread_mutex_destroy(&tok->lock);
#endif
free(tok);
}
/**
* xmlMutexLock:
* @tok: the simple mutex
*
* xmlMutexLock() is used to lock a libxml2 token.
*/
void
xmlMutexLock(xmlMutexPtr tok)
{
if (tok == NULL)
return;
#ifdef HAVE_PTHREAD_H
pthread_mutex_lock(&tok->lock);
#endif
}
/**
* xmlMutexUnlock:
* @tok: the simple mutex
*
* xmlMutexUnlock() is used to unlock a libxml2 token.
*/
void
xmlMutexUnlock(xmlMutexPtr tok)
{
if (tok == NULL)
return;
#ifdef HAVE_PTHREAD_H
pthread_mutex_unlock(&tok->lock);
#endif
}
/**
* xmlNewRMutex:
*
* xmlRNewMutex() is used to allocate a reentrant mutex for use in
* synchronizing access to data. token_r is a re-entrant lock and thus useful
* for synchronizing access to data structures that may be manipulated in a
* recursive fashion.
*
* Returns the new reentrant mutex pointer or NULL in case of error
*/
xmlRMutexPtr
xmlNewRMutex(void)
{
xmlRMutexPtr tok;
if ((tok = (xmlRMutexPtr)malloc(sizeof(xmlRMutex))) == NULL)
return (NULL);
#ifdef HAVE_PTHREAD_H
pthread_mutex_init(&tok->lock, NULL);
tok->held = 0;
tok->waiters = 0;
pthread_cond_init(&tok->cv, NULL);
#endif
return (tok);
}
#ifndef XMLENGINE_EXCLUDE_UNUSED
/**
* xmlFreeRMutex:
* @tok: the reentrant mutex
*
* xmlRFreeMutex() is used to reclaim resources associated with a
* reentrant mutex.
*/
void
xmlFreeRMutex(xmlRMutexPtr tok ATTRIBUTE_UNUSED)
{
#ifdef HAVE_PTHREAD_H
pthread_mutex_destroy(&tok->lock);
#endif
free(tok);
}
#endif /* ifndef XMLENGINE_EXCLUDE_UNUSED */
/**
* xmlRMutexLock:
* @tok: the reentrant mutex
*
* xmlRMutexLock() is used to lock a libxml2 token_r.
*/
void
xmlRMutexLock(xmlRMutexPtr tok)
{
if (tok == NULL)
return;
#ifdef HAVE_PTHREAD_H
pthread_mutex_lock(&tok->lock);
if (tok->held) {
if (pthread_equal(tok->tid, pthread_self())) {
tok->held++;
pthread_mutex_unlock(&tok->lock);
return;
} else {
tok->waiters++;
while (tok->held)
pthread_cond_wait(&tok->cv, &tok->lock);
tok->waiters--;
}
}
tok->tid = pthread_self();
tok->held = 1;
pthread_mutex_unlock(&tok->lock);
#endif
}
/**
* xmlRMutexUnlock:
* @tok: the reentrant mutex
*
* xmlRMutexUnlock() is used to unlock a libxml2 token_r.
*/
void
xmlRMutexUnlock(xmlRMutexPtr tok ATTRIBUTE_UNUSED)
{
if (tok == NULL)
return;
#ifdef HAVE_PTHREAD_H
pthread_mutex_lock(&tok->lock);
tok->held--;
if (tok->held == 0) {
if (tok->waiters)
pthread_cond_signal(&tok->cv);
tok->tid = 0;
}
pthread_mutex_unlock(&tok->lock);
#endif
}
/*************************************************************************
* *
* Per thread global state handling *
* *
************************************************************************/
#ifdef LIBXML_THREAD_ENABLED
/**
* xmlFreeGlobalState:
* @state: a thread global state
*
* xmlFreeGlobalState() is called when a thread terminates with a non-NULL
* global state. It is is used here to reclaim memory resources.
*/
static void
xmlFreeGlobalState(void *state)
{
free(state);
}
/**
* xmlNewGlobalState:
* @stackLimit: the address which the stack pointer would contain if the
* stack were full
*
* xmlNewGlobalState() allocates a global state. This structure is used to
* hold all data for use by a thread when supporting backwards compatibility
* of libxml2 to pre-thread-safe behaviour.
*
* Returns the newly allocated xmlGlobalStatePtr or NULL in case of error
*/
static xmlGlobalStatePtr
xmlNewGlobalState(unsigned int stackLimit)
{
xmlGlobalState *gs;
gs = malloc(sizeof(xmlGlobalState));
if (gs == NULL)
return(NULL);
memset(gs, 0, sizeof(xmlGlobalState));
xmlInitializeGlobalState(gs, stackLimit);
return (gs);
}
#endif /* LIBXML_THREAD_ENABLED */
/************************************************************************
* *
* Library wide thread interfaces *
* *
************************************************************************/
/**
* xmlGetThreadId:
*
* xmlGetThreadId() find the current thread ID number
*
* Returns the current thread ID number
*/
int
xmlGetThreadId(void)
{
#ifdef HAVE_PTHREAD_H
return((int) pthread_self());
#else
return((int) 0);
#endif
}
/**
* xmlIsMainThread:
*
* xmlIsMainThread() check whether the current thread is the main thread.
*
* Returns 1 if the current thread is the main thread, 0 otherwise
*/
int
xmlIsMainThread(void)
{
#ifdef HAVE_PTHREAD_H
pthread_once(&once_control, xmlOnceInit);
#endif
#ifdef DEBUG_THREADS
xmlGenericError(xmlGenericErrorContext, "xmlIsMainThread()\n");
#endif
#ifdef HAVE_PTHREAD_H
return(mainthread == pthread_self());
#else
return(1);
#endif
}
/**
* xmlLockLibrary:
*
* xmlLockLibrary() is used to take out a re-entrant lock on the libxml2
* library.
*/
void
xmlLockLibrary(void)
{
#ifdef DEBUG_THREADS
xmlGenericError(xmlGenericErrorContext, "xmlLockLibrary()\n");
#endif
xmlRMutexLock(xmlLibraryLock);
}
/**
* xmlUnlockLibrary:
*
* xmlUnlockLibrary() is used to release a re-entrant lock on the libxml2
* library.
*/
void
xmlUnlockLibrary(void)
{
#ifdef DEBUG_THREADS
xmlGenericError(xmlGenericErrorContext, "xmlUnlockLibrary()\n");
#endif
xmlRMutexUnlock(xmlLibraryLock);
}
/**
* xmlInitThreads:
*
* xmlInitThreads() is used to to initialize all the thread related
* data of the libxml2 library.
*/
void
xmlInitThreads(void)
{
#ifdef DEBUG_THREADS
xmlGenericError(xmlGenericErrorContext, "xmlInitThreads()\n");
#endif
}
/**
* xmlCleanupThreads:
*
* xmlCleanupThreads() is used to to cleanup all the thread related
* data of the libxml2 library once processing has ended.
*/
void
xmlCleanupThreads(void)
{
#ifdef DEBUG_THREADS
xmlGenericError(xmlGenericErrorContext, "xmlCleanupThreads()\n");
#endif
}
#ifdef LIBXML_THREAD_ENABLED
/**
* xmlOnceInit
*
* xmlOnceInit() is used to initialize the value of mainthread for use
* in other routines. This function should only be called using
* pthread_once() in association with the once_control variable to ensure
* that the function is only called once. See man pthread_once for more
* details.
*/
static void
xmlOnceInit(void) {
#ifdef HAVE_PTHREAD_H
(void) pthread_key_create(&globalkey, xmlFreeGlobalState);
mainthread = pthread_self();
#endif
}
#endif