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