From c59abe25892e32c803ec527c40e9a74ab31ea58a Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 10 May 2012 18:44:07 +0200
Subject: Use semaphores instead of condition variables

---
 src/util.h | 71 +++++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 56 insertions(+), 15 deletions(-)

(limited to 'src/util.h')

diff --git a/src/util.h b/src/util.h
index ebd574f896..61ff553539 100644
--- a/src/util.h
+++ b/src/util.h
@@ -23,7 +23,7 @@ typedef int pid_t; /* define for windows compatiblity */
 #include <boost/filesystem/path.hpp>
 #include <boost/interprocess/sync/interprocess_recursive_mutex.hpp>
 #include <boost/interprocess/sync/scoped_lock.hpp>
-#include <boost/interprocess/sync/interprocess_condition.hpp>
+#include <boost/interprocess/sync/interprocess_semaphore.hpp>
 #include <boost/interprocess/sync/lock_options.hpp>
 #include <boost/date_time/gregorian/gregorian_types.hpp>
 #include <boost/date_time/posix_time/posix_time_types.hpp>
@@ -275,24 +275,10 @@ public:
 };
 
 typedef CMutexLock<CCriticalSection> CCriticalBlock;
-typedef CMutexLock<CWaitableCriticalSection> CWaitableCriticalBlock;
-typedef boost::interprocess::interprocess_condition CConditionVariable;
-
-/** Wait for a given condition inside a WAITABLE_CRITICAL_BLOCK */
-#define WAIT(name,condition) \
-   do { while(!(condition)) { (name).wait(waitablecriticalblock.GetLock()); } } while(0)
-
-/** Notify waiting threads that a condition may hold now */
-#define NOTIFY(name) \
-   do { (name).notify_one(); } while(0)
-
-#define NOTIFY_ALL(name) \
-   do { (name).notify_all(); } while(0)
 
 #define LOCK(cs) CCriticalBlock criticalblock(cs, #cs, __FILE__, __LINE__)
 #define LOCK2(cs1,cs2) CCriticalBlock criticalblock1(cs1, #cs1, __FILE__, __LINE__),criticalblock2(cs2, #cs2, __FILE__, __LINE__)
 #define TRY_LOCK(cs,name) CCriticalBlock name(cs, #cs, __FILE__, __LINE__, true)
-#define WAITABLE_LOCK(cs) CWaitableCriticalBlock waitablecriticalblock(cs, #cs, __FILE__, __LINE__)
 
 #define ENTER_CRITICAL_SECTION(cs) \
     { \
@@ -306,6 +292,61 @@ typedef boost::interprocess::interprocess_condition CConditionVariable;
         LeaveCritical(); \
     }
 
+typedef boost::interprocess::interprocess_semaphore CSemaphore;
+
+/** RAII-style semaphore lock */
+class CSemaphoreGrant
+{
+private:
+    CSemaphore *sem;
+    bool fHaveGrant;
+
+public:
+    void Acquire() {
+        if (fHaveGrant)
+            return;
+        sem->wait();
+        fHaveGrant = true;
+    }
+
+    void Release() {
+        if (!fHaveGrant)
+            return;
+        sem->post();
+        fHaveGrant = false;
+    }
+
+    bool TryAcquire() {
+        if (!fHaveGrant && sem->try_wait())
+            fHaveGrant = true;
+        return fHaveGrant;
+    }
+
+    void MoveTo(CSemaphoreGrant &grant) {
+        grant.Release();
+        grant.sem = sem;
+        grant.fHaveGrant = fHaveGrant;
+        sem = NULL;
+        fHaveGrant = false;
+    }
+
+    CSemaphoreGrant() : sem(NULL), fHaveGrant(false) {}
+
+    CSemaphoreGrant(CSemaphore &sema, bool fTry = false) : sem(&sema), fHaveGrant(false) {
+        if (fTry)
+            TryAcquire();
+        else
+            Acquire();
+    }
+
+    ~CSemaphoreGrant() {
+        Release();
+    }
+
+    operator bool() {
+        return fHaveGrant;
+    }
+};
 
 inline std::string i64tostr(int64 n)
 {
-- 
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