From c065984b58000a44c90588198d222a314ac532fd Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Wed, 22 Jan 2014 15:26:21 +0000
Subject: [PATCH] Add a read/write lock implementation

Add virRWLock backed up by a POSIX rwlock primitive

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 src/libvirt_private.syms    |  5 +++++
 src/util/virthread.h        | 10 ++++++++++
 src/util/virthreadpthread.c | 33 +++++++++++++++++++++++++++++++++
 src/util/virthreadpthread.h |  4 ++++
 src/util/virthreadwin32.c   | 19 +++++++++++++++++++
 src/util/virthreadwin32.h   |  4 ++++
 6 files changed, 75 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index f890c6ecee..94901c7ef0 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1818,6 +1818,11 @@ virMutexInitRecursive;
 virMutexLock;
 virMutexUnlock;
 virOnce;
+virRWLockDestroy;
+virRWLockInit;
+virRWLockRead;
+virRWLockUnlock;
+virRWLockWrite;
 virThreadCancel;
 virThreadCreate;
 virThreadID;
diff --git a/src/util/virthread.h b/src/util/virthread.h
index 84d3bdc828..7015d60082 100644
--- a/src/util/virthread.h
+++ b/src/util/virthread.h
@@ -28,6 +28,9 @@
 typedef struct virMutex virMutex;
 typedef virMutex *virMutexPtr;
 
+typedef struct virRWLock virRWLock;
+typedef virRWLock *virRWLockPtr;
+
 typedef struct virCond virCond;
 typedef virCond *virCondPtr;
 
@@ -89,6 +92,13 @@ void virMutexLock(virMutexPtr m);
 void virMutexUnlock(virMutexPtr m);
 
 
+int virRWLockInit(virRWLockPtr m) ATTRIBUTE_RETURN_CHECK;
+void virRWLockDestroy(virRWLockPtr m);
+
+void virRWLockRead(virRWLockPtr m);
+void virRWLockWrite(virRWLockPtr m);
+void virRWLockUnlock(virRWLockPtr m);
+
 
 int virCondInit(virCondPtr c) ATTRIBUTE_RETURN_CHECK;
 int virCondDestroy(virCondPtr c);
diff --git a/src/util/virthreadpthread.c b/src/util/virthreadpthread.c
index ca841e4978..38b6454c27 100644
--- a/src/util/virthreadpthread.c
+++ b/src/util/virthreadpthread.c
@@ -91,6 +91,39 @@ void virMutexUnlock(virMutexPtr m)
 }
 
 
+int virRWLockInit(virRWLockPtr m)
+{
+    int ret;
+    ret = pthread_rwlock_init(&m->lock, NULL);
+    if (ret != 0) {
+        errno = ret;
+        return -1;
+    }
+    return 0;
+}
+
+void virRWLockDestroy(virRWLockPtr m)
+{
+    pthread_rwlock_destroy(&m->lock);
+}
+
+
+void virRWLockRead(virRWLockPtr m)
+{
+    pthread_rwlock_rdlock(&m->lock);
+}
+
+void virRWLockWrite(virRWLockPtr m)
+{
+    pthread_rwlock_wrlock(&m->lock);
+}
+
+
+void virRWLockUnlock(virRWLockPtr m)
+{
+    pthread_rwlock_unlock(&m->lock);
+}
+
 int virCondInit(virCondPtr c)
 {
     int ret;
diff --git a/src/util/virthreadpthread.h b/src/util/virthreadpthread.h
index b9f1319fc1..cb607d0d72 100644
--- a/src/util/virthreadpthread.h
+++ b/src/util/virthreadpthread.h
@@ -27,6 +27,10 @@ struct virMutex {
     pthread_mutex_t lock;
 };
 
+struct virRWLock {
+    pthread_rwlock_t lock;
+};
+
 struct virCond {
     pthread_cond_t cond;
 };
diff --git a/src/util/virthreadwin32.c b/src/util/virthreadwin32.c
index 5d6277f246..a9e235384e 100644
--- a/src/util/virthreadwin32.c
+++ b/src/util/virthreadwin32.c
@@ -123,6 +123,25 @@ void virMutexUnlock(virMutexPtr m)
 }
 
 
+int virRWLockInit(virRWLockPtr m ATTRIBUTE_UNUSED)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
+void virRWLockDestroy(virRWLockPtr m ATTRIBUTE_UNUSED)
+{}
+
+
+void virRWLockRead(virRWLockPtr m ATTRIBUTE_UNUSED)
+{}
+
+void virRWLockWrite(virRWLockPtr m ATTRIBUTE_UNUSED)
+{}
+
+
+void virRWLockUnlock(virRWLockPtr m ATTRIBUTE_UNUSED)
+{}
 
 int virCondInit(virCondPtr c)
 {
diff --git a/src/util/virthreadwin32.h b/src/util/virthreadwin32.h
index 645031b696..31d9444cc1 100644
--- a/src/util/virthreadwin32.h
+++ b/src/util/virthreadwin32.h
@@ -30,6 +30,10 @@ struct virMutex {
     HANDLE lock;
 };
 
+struct virRWLock {
+    bool ignored;
+};
+
 struct virCond {
     virMutex lock;
     size_t nwaiters;