+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab
-/*
- * Ceph - scalable distributed file system
- *
- * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
- *
- * This is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License version 2.1, as published by the Free Software
- * Foundation. See file COPYING.
- *
- */
-
-
-
-#ifndef CEPH_RWLock_Posix__H
-#define CEPH_RWLock_Posix__H
-
-#include <pthread.h>
-#include <string>
-#include <include/assert.h>
-#include "lockdep.h"
-#include "common/valgrind.h"
-
-#include <atomic>
-
-class RWLock final
-{
- mutable pthread_rwlock_t L;
- std::string name;
- mutable int id;
- mutable std::atomic<unsigned> nrlock = { 0 }, nwlock = { 0 };
- bool track, lockdep;
-
- std::string unique_name(const char* name) const;
-
-public:
- RWLock(const RWLock& other) = delete;
- const RWLock& operator=(const RWLock& other) = delete;
-
- RWLock(const std::string &n, bool track_lock=true, bool ld=true, bool prioritize_write=false)
- : name(n), id(-1), track(track_lock),
- lockdep(ld) {
-#if defined(PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP)
- if (prioritize_write) {
- pthread_rwlockattr_t attr;
- pthread_rwlockattr_init(&attr);
- // PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
- // Setting the lock kind to this avoids writer starvation as long as
- // long as any read locking is not done in a recursive fashion.
- pthread_rwlockattr_setkind_np(&attr,
- PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
- pthread_rwlock_init(&L, &attr);
- } else
-#endif
- // Next block is in {} to possibly connect to the above if when code is used.
- {
- pthread_rwlock_init(&L, NULL);
- }
- ANNOTATE_BENIGN_RACE_SIZED(&id, sizeof(id), "RWLock lockdep id");
- ANNOTATE_BENIGN_RACE_SIZED(&nrlock, sizeof(nrlock), "RWlock nrlock");
- ANNOTATE_BENIGN_RACE_SIZED(&nwlock, sizeof(nwlock), "RWlock nwlock");
- if (lockdep && g_lockdep) id = lockdep_register(name.c_str());
- }
-
- bool is_locked() const {
- assert(track);
- return (nrlock > 0) || (nwlock > 0);
- }
-
- bool is_wlocked() const {
- assert(track);
- return (nwlock > 0);
- }
- ~RWLock() {
- // The following check is racy but we are about to destroy
- // the object and we assume that there are no other users.
- if (track)
- assert(!is_locked());
- pthread_rwlock_destroy(&L);
- if (lockdep && g_lockdep) {
- lockdep_unregister(id);
- }
- }
-
- void unlock(bool lockdep=true) const {
- if (track) {
- if (nwlock > 0) {
- nwlock--;
- } else {
- assert(nrlock > 0);
- nrlock--;
- }
- }
- if (lockdep && this->lockdep && g_lockdep)
- id = lockdep_will_unlock(name.c_str(), id);
- int r = pthread_rwlock_unlock(&L);
- assert(r == 0);
- }
-
- // read
- void get_read() const {
- if (lockdep && g_lockdep) id = lockdep_will_lock(name.c_str(), id);
- int r = pthread_rwlock_rdlock(&L);
- assert(r == 0);
- if (lockdep && g_lockdep) id = lockdep_locked(name.c_str(), id);
- if (track)
- nrlock++;
- }
- bool try_get_read() const {
- if (pthread_rwlock_tryrdlock(&L) == 0) {
- if (track)
- nrlock++;
- if (lockdep && g_lockdep) id = lockdep_locked(name.c_str(), id);
- return true;
- }
- return false;
- }
- void put_read() const {
- unlock();
- }
-
- // write
- void get_write(bool lockdep=true) {
- if (lockdep && this->lockdep && g_lockdep)
- id = lockdep_will_lock(name.c_str(), id);
- int r = pthread_rwlock_wrlock(&L);
- assert(r == 0);
- if (lockdep && this->lockdep && g_lockdep)
- id = lockdep_locked(name.c_str(), id);
- if (track)
- nwlock++;
-
- }
- bool try_get_write(bool lockdep=true) {
- if (pthread_rwlock_trywrlock(&L) == 0) {
- if (lockdep && this->lockdep && g_lockdep)
- id = lockdep_locked(name.c_str(), id);
- if (track)
- nwlock++;
- return true;
- }
- return false;
- }
- void put_write() {
- unlock();
- }
-
- void get(bool for_write) {
- if (for_write) {
- get_write();
- } else {
- get_read();
- }
- }
-
-public:
- class RLocker {
- const RWLock &m_lock;
-
- bool locked;
-
- public:
- explicit RLocker(const RWLock& lock) : m_lock(lock) {
- m_lock.get_read();
- locked = true;
- }
- void unlock() {
- assert(locked);
- m_lock.unlock();
- locked = false;
- }
- ~RLocker() {
- if (locked) {
- m_lock.unlock();
- }
- }
- };
-
- class WLocker {
- RWLock &m_lock;
-
- bool locked;
-
- public:
- explicit WLocker(RWLock& lock) : m_lock(lock) {
- m_lock.get_write();
- locked = true;
- }
- void unlock() {
- assert(locked);
- m_lock.unlock();
- locked = false;
- }
- ~WLocker() {
- if (locked) {
- m_lock.unlock();
- }
- }
- };
-
- class Context {
- RWLock& lock;
-
- public:
- enum LockState {
- Untaken = 0,
- TakenForRead = 1,
- TakenForWrite = 2,
- };
-
- private:
- LockState state;
-
- public:
- explicit Context(RWLock& l) : lock(l), state(Untaken) {}
- Context(RWLock& l, LockState s) : lock(l), state(s) {}
-
- void get_write() {
- assert(state == Untaken);
-
- lock.get_write();
- state = TakenForWrite;
- }
-
- void get_read() {
- assert(state == Untaken);
-
- lock.get_read();
- state = TakenForRead;
- }
-
- void unlock() {
- assert(state != Untaken);
- lock.unlock();
- state = Untaken;
- }
-
- void promote() {
- assert(state == TakenForRead);
- unlock();
- get_write();
- }
-
- LockState get_state() { return state; }
- void set_state(LockState s) {
- state = s;
- }
-
- bool is_locked() {
- return (state != Untaken);
- }
-
- bool is_rlocked() {
- return (state == TakenForRead);
- }
-
- bool is_wlocked() {
- return (state == TakenForWrite);
- }
- };
-};
-
-#endif // !CEPH_RWLock_Posix__H
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