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