prthread.h
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- /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
- /* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is the Netscape Portable Runtime (NSPR).
- *
- * The Initial Developer of the Original Code is
- * Netscape Communications Corporation.
- * Portions created by the Initial Developer are Copyright (C) 1998-2000
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
- #ifndef prthread_h___
- #define prthread_h___
- /*
- ** API for NSPR threads. On some architectures (MAC and WIN16
- ** notably) pre-emptibility is not guaranteed. Hard priority scheduling
- ** is not guaranteed, so programming using priority based synchronization
- ** is a no-no.
- **
- ** NSPR threads are scheduled based loosely on their client set priority.
- ** In general, a thread of a higher priority has a statistically better
- ** chance of running relative to threads of lower priority. However,
- ** NSPR uses multiple strategies to provide execution vehicles for thread
- ** abstraction of various host platforms. As it turns out, there is little
- ** NSPR can do to affect the scheduling attributes of "GLOBAL" threads.
- ** However, a semblance of GLOBAL threads is used to implement "LOCAL"
- ** threads. An arbitrary number of such LOCAL threads can be assigned to
- ** a single GLOBAL thread.
- **
- ** For scheduling, NSPR will attempt to run the highest priority LOCAL
- ** thread associated with a given GLOBAL thread. It is further assumed
- ** that the host OS will apply some form of "fair" scheduling on the
- ** GLOBAL threads.
- **
- ** Threads have a "system flag" which when set indicates the thread
- ** doesn't count for determining when the process should exit (the
- ** process exits when the last user thread exits).
- **
- ** Threads also have a "scope flag" which controls whether the threads
- ** are scheduled in the local scope or scheduled by the OS globally. This
- ** indicates whether a thread is permanently bound to a native OS thread.
- ** An unbound thread competes for scheduling resources in the same process.
- **
- ** Another flag is "state flag" which control whether the thread is joinable.
- ** It allows other threads to wait for the created thread to reach completion.
- **
- ** Threads can have "per-thread-data" attached to them. Each thread has a
- ** per-thread error number and error string which are updated when NSPR
- ** operations fail.
- */
- #include "prtypes.h"
- #include "prinrval.h"
- PR_BEGIN_EXTERN_C
- typedef struct PRThread PRThread;
- typedef struct PRThreadStack PRThreadStack;
- typedef enum PRThreadType {
- PR_USER_THREAD,
- PR_SYSTEM_THREAD
- } PRThreadType;
- typedef enum PRThreadScope {
- PR_LOCAL_THREAD,
- PR_GLOBAL_THREAD,
- PR_GLOBAL_BOUND_THREAD
- } PRThreadScope;
- typedef enum PRThreadState {
- PR_JOINABLE_THREAD,
- PR_UNJOINABLE_THREAD
- } PRThreadState;
- typedef enum PRThreadPriority
- {
- PR_PRIORITY_FIRST = 0, /* just a placeholder */
- PR_PRIORITY_LOW = 0, /* the lowest possible priority */
- PR_PRIORITY_NORMAL = 1, /* most common expected priority */
- PR_PRIORITY_HIGH = 2, /* slightly more aggressive scheduling */
- PR_PRIORITY_URGENT = 3, /* it does little good to have more than one */
- PR_PRIORITY_LAST = 3 /* this is just a placeholder */
- } PRThreadPriority;
- /*
- ** Create a new thread:
- ** "type" is the type of thread to create
- ** "start(arg)" will be invoked as the threads "main"
- ** "priority" will be created thread's priority
- ** "scope" will specify whether the thread is local or global
- ** "state" will specify whether the thread is joinable or not
- ** "stackSize" the size of the stack, in bytes. The value can be zero
- ** and then a machine specific stack size will be chosen.
- **
- ** This can return NULL if some kind of error occurs, such as if memory is
- ** tight.
- **
- ** If you want the thread to start up waiting for the creator to do
- ** something, enter a lock before creating the thread and then have the
- ** threads start routine enter and exit the same lock. When you are ready
- ** for the thread to run, exit the lock.
- **
- ** If you want to detect the completion of the created thread, the thread
- ** should be created joinable. Then, use PR_JoinThread to synchrnoize the
- ** termination of another thread.
- **
- ** When the start function returns the thread exits. If it is the last
- ** PR_USER_THREAD to exit then the process exits.
- */
- NSPR_API(PRThread*) PR_CreateThread(PRThreadType type,
- void (PR_CALLBACK *start)(void *arg),
- void *arg,
- PRThreadPriority priority,
- PRThreadScope scope,
- PRThreadState state,
- PRUint32 stackSize);
- /*
- ** Wait for thread termination:
- ** "thread" is the target thread
- **
- ** This can return PR_FAILURE if no joinable thread could be found
- ** corresponding to the specified target thread.
- **
- ** The calling thread is blocked until the target thread completes.
- ** Several threads cannot wait for the same thread to complete; one thread
- ** will operate successfully and others will terminate with an error PR_FAILURE.
- ** The calling thread will not be blocked if the target thread has already
- ** terminated.
- */
- NSPR_API(PRStatus) PR_JoinThread(PRThread *thread);
- /*
- ** Return the current thread object for the currently running code.
- ** Never returns NULL.
- */
- NSPR_API(PRThread*) PR_GetCurrentThread(void);
- #ifndef NO_NSPR_10_SUPPORT
- #define PR_CurrentThread() PR_GetCurrentThread() /* for nspr1.0 compat. */
- #endif /* NO_NSPR_10_SUPPORT */
- /*
- ** Get the priority of "thread".
- */
- NSPR_API(PRThreadPriority) PR_GetThreadPriority(const PRThread *thread);
- /*
- ** Change the priority of the "thread" to "priority".
- */
- NSPR_API(void) PR_SetThreadPriority(PRThread *thread, PRThreadPriority priority);
- /*
- ** This routine returns a new index for per-thread-private data table.
- ** The index is visible to all threads within a process. This index can
- ** be used with the PR_SetThreadPrivate() and PR_GetThreadPrivate() routines
- ** to save and retrieve data associated with the index for a thread.
- **
- ** Each index is associationed with a destructor function ('dtor'). The function
- ** may be specified as NULL when the index is created. If it is not NULL, the
- ** function will be called when:
- ** - the thread exits and the private data for the associated index
- ** is not NULL,
- ** - new thread private data is set and the current private data is
- ** not NULL.
- **
- ** The index independently maintains specific values for each binding thread.
- ** A thread can only get access to its own thread-specific-data.
- **
- ** Upon a new index return the value associated with the index for all threads
- ** is NULL, and upon thread creation the value associated with all indices for
- ** that thread is NULL.
- **
- ** Returns PR_FAILURE if the total number of indices will exceed the maximun
- ** allowed.
- */
- typedef void (PR_CALLBACK *PRThreadPrivateDTOR)(void *priv);
- NSPR_API(PRStatus) PR_NewThreadPrivateIndex(
- PRUintn *newIndex, PRThreadPrivateDTOR destructor);
- /*
- ** Define some per-thread-private data.
- ** "tpdIndex" is an index into the per-thread private data table
- ** "priv" is the per-thread-private data
- **
- ** If the per-thread private data table has a previously registered
- ** destructor function and a non-NULL per-thread-private data value,
- ** the destructor function is invoked.
- **
- ** This can return PR_FAILURE if the index is invalid.
- */
- NSPR_API(PRStatus) PR_SetThreadPrivate(PRUintn tpdIndex, void *priv);
- /*
- ** Recover the per-thread-private data for the current thread. "tpdIndex" is
- ** the index into the per-thread private data table.
- **
- ** The returned value may be NULL which is indistinguishable from an error
- ** condition.
- **
- ** A thread can only get access to its own thread-specific-data.
- */
- NSPR_API(void*) PR_GetThreadPrivate(PRUintn tpdIndex);
- /*
- ** This routine sets the interrupt request for a target thread. The interrupt
- ** request remains in the thread's state until it is delivered exactly once
- ** or explicitly canceled.
- **
- ** A thread that has been interrupted will fail all NSPR blocking operations
- ** that return a PRStatus (I/O, waiting on a condition, etc).
- **
- ** PR_Interrupt may itself fail if the target thread is invalid.
- */
- NSPR_API(PRStatus) PR_Interrupt(PRThread *thread);
- /*
- ** Clear the interrupt request for the calling thread. If no such request
- ** is pending, this operation is a noop.
- */
- NSPR_API(void) PR_ClearInterrupt(void);
- /*
- ** Block the interrupt for the calling thread.
- */
- NSPR_API(void) PR_BlockInterrupt(void);
- /*
- ** Unblock the interrupt for the calling thread.
- */
- NSPR_API(void) PR_UnblockInterrupt(void);
- /*
- ** Make the current thread sleep until "ticks" time amount of time
- ** has expired. If "ticks" is PR_INTERVAL_NO_WAIT then the call is
- ** equivalent to calling PR_Yield. Calling PR_Sleep with an argument
- ** equivalent to PR_INTERVAL_NO_TIMEOUT is an error and will result
- ** in a PR_FAILURE error return.
- */
- NSPR_API(PRStatus) PR_Sleep(PRIntervalTime ticks);
- /*
- ** Get the scoping of this thread.
- */
- NSPR_API(PRThreadScope) PR_GetThreadScope(const PRThread *thread);
- /*
- ** Get the type of this thread.
- */
- NSPR_API(PRThreadType) PR_GetThreadType(const PRThread *thread);
- /*
- ** Get the join state of this thread.
- */
- NSPR_API(PRThreadState) PR_GetThreadState(const PRThread *thread);
- PR_END_EXTERN_C
- #endif /* prthread_h___ */