haiku/headers/private/kernel/condition_variable.h

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/*
* Introduced a set of functions (thread_prepare_to_block(), thread_block(), thread_unblock(),...) that allow a thread to wait for something without needing a semaphore or condition variable. It can simply block and another thread can unblock it. Supports timeouts and interrupting. Both semaphores and condition variables use this common mechanism, now. * Semaphores: - Some simplifications due to the thread blocking mechanism. - Changed locking order to sem -> thread. It was the other way around before and when introducing the wait_for_objects() support I had also introduced a situation where the locking was reverse, which could potentially cause a dead lock on SMP systems. - Instead of queueing thread structures, a semaphore queues queued_thread entries now, which are created on the stack. The thread::sem structure could thus be removed. - Added sem_entry::net_count, which is sem_entry::count plus the acquisition count of all waiting threads. This number is needed in remove_thread_from_sem() and instead of computing it there we maintain it. - Fixed remove_thread_from_sem(). It would not unblock threads, if the sem count was <= 0. - Made sem::last_acquirer unconditional. It is actually needed for sem_info::latest_holder. Fixed fill_sem_info() accordingly. - Added some optional tracing output, though only via ktrace_printf(). * Condition variables: - Could be simplified significantly through the use of the thread blocking mechanism. Removed a good deal of unnecessary code. - Moved the ConditionVariableEntry "flags" parameter from Wait() to Add(), and adjusted all places where condition variables are used accordingly. * snooze() uses thread_block_with_timeout() instead of a semaphore. * Simplified thread interrupting in the signal and user debugger code. Instead of separate functions for threads waiting on a semaphore or condititon variable, we only have a single thread_interrupt(), now. git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25099 a95241bf-73f2-0310-859d-f6bbb57e9c96
2008-04-22 20:22:42 +04:00
* Copyright 2007-2008, Ingo Weinhold, bonefish@cs.tu-berlin.de.
* Distributed under the terms of the MIT License.
*/
#ifndef _KERNEL_CONDITION_VARIABLE_H
#define _KERNEL_CONDITION_VARIABLE_H
#include <OS.h>
#include <debug.h>
#ifdef __cplusplus
#include <util/DoublyLinkedList.h>
#include <util/OpenHashTable.h>
class ConditionVariable;
struct ConditionVariableEntry
: DoublyLinkedListLinkImpl<ConditionVariableEntry> {
public:
#if KDEBUG
inline ConditionVariableEntry();
inline ~ConditionVariableEntry();
#endif
bool Add(const void* object);
status_t Wait(uint32 flags = 0, bigtime_t timeout = 0);
status_t Wait(const void* object, uint32 flags = 0,
bigtime_t timeout = 0);
inline ConditionVariable* Variable() const { return fVariable; }
private:
inline void AddToVariable(ConditionVariable* variable);
private:
ConditionVariable* fVariable;
struct thread* fThread;
status_t fWaitStatus;
friend class ConditionVariable;
};
class ConditionVariable : protected HashTableLink<ConditionVariable> {
public:
void Init(const void* object,
const char* objectType);
// for anonymous (unpublished) cvars
void Publish(const void* object,
const char* objectType);
void Unpublish(bool threadsLocked = false);
inline void NotifyOne(bool threadsLocked = false);
inline void NotifyAll(bool threadsLocked = false);
void Add(ConditionVariableEntry* entry);
status_t Wait(uint32 flags = 0, bigtime_t timeout = 0);
// all-in one, i.e. doesn't need a
// ConditionVariableEntry
const void* Object() const { return fObject; }
const char* ObjectType() const { return fObjectType; }
static void ListAll();
void Dump() const;
private:
void _Notify(bool all, bool threadsLocked);
void _NotifyChecked(bool all, status_t result);
protected:
typedef DoublyLinkedList<ConditionVariableEntry> EntryList;
const void* fObject;
const char* fObjectType;
EntryList fEntries;
friend class ConditionVariableEntry;
friend class ConditionVariableHashDefinition;
};
#if KDEBUG
inline
ConditionVariableEntry::ConditionVariableEntry()
: fVariable(NULL)
{
}
inline
ConditionVariableEntry::~ConditionVariableEntry()
{
if (fVariable != NULL) {
panic("Destroying condition variable entry %p, but it's still "
"attached to variable %p\n", this, fVariable);
}
}
#endif
inline void
ConditionVariable::NotifyOne(bool threadsLocked)
{
_Notify(false, threadsLocked);
}
inline void
ConditionVariable::NotifyAll(bool threadsLocked)
{
_Notify(true, threadsLocked);
}
extern "C" {
#endif // __cplusplus
extern void condition_variable_init();
#ifdef __cplusplus
} // extern "C"
#endif
#endif /* _KERNEL_CONDITION_VARIABLE_H */