From af370c702a1374fd8997cedd5f2ce5d5f153dcb3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Axel=20D=C3=B6rfler?= <axeld@pinc-software.de>
Date: Mon, 7 Jul 2008 16:17:34 +0000
Subject: [PATCH] * Added a recursive_lock_trylock() function.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26297 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 headers/private/fs_shell/fssh_api_wrapper.h |  1 +
 headers/private/fs_shell/fssh_lock.h        |  1 +
 headers/private/kernel/lock.h               |  1 +
 src/system/kernel/lock.cpp                  | 27 ++++++++++++++++++++-
 src/tools/fs_shell/lock.cpp                 | 18 ++++++++++++++
 5 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/headers/private/fs_shell/fssh_api_wrapper.h b/headers/private/fs_shell/fssh_api_wrapper.h
index 9daea616b5..bd4ac10d60 100644
--- a/headers/private/fs_shell/fssh_api_wrapper.h
+++ b/headers/private/fs_shell/fssh_api_wrapper.h
@@ -975,6 +975,7 @@
 #define recursive_lock_init_etc		fssh_recursive_lock_init_etc
 #define recursive_lock_destroy		fssh_recursive_lock_destroy
 #define recursive_lock_lock			fssh_recursive_lock_lock
+#define recursive_lock_trylock		fssh_recursive_lock_trylock
 #define recursive_lock_unlock		fssh_recursive_lock_unlock
 #define recursive_lock_get_recursion fssh_recursive_lock_get_recursion
 
diff --git a/headers/private/fs_shell/fssh_lock.h b/headers/private/fs_shell/fssh_lock.h
index c44c84ad68..8e591d5a2c 100644
--- a/headers/private/fs_shell/fssh_lock.h
+++ b/headers/private/fs_shell/fssh_lock.h
@@ -55,6 +55,7 @@ extern void fssh_recursive_lock_init_etc(fssh_recursive_lock *lock, const char *
 	uint32_t flags);
 extern void fssh_recursive_lock_destroy(fssh_recursive_lock *lock);
 extern fssh_status_t fssh_recursive_lock_lock(fssh_recursive_lock *lock);
+extern fssh_status_t fssh_recursive_lock_trylock(fssh_recursive_lock *lock);
 extern void fssh_recursive_lock_unlock(fssh_recursive_lock *lock);
 extern int32_t fssh_recursive_lock_get_recursion(fssh_recursive_lock *lock);
 
diff --git a/headers/private/kernel/lock.h b/headers/private/kernel/lock.h
index a6dcb625df..308dfeb323 100644
--- a/headers/private/kernel/lock.h
+++ b/headers/private/kernel/lock.h
@@ -84,6 +84,7 @@ extern void recursive_lock_init_etc(recursive_lock *lock, const char *name,
 	uint32 flags);
 extern void recursive_lock_destroy(recursive_lock *lock);
 extern status_t recursive_lock_lock(recursive_lock *lock);
+extern status_t recursive_lock_trylock(recursive_lock *lock);
 extern void recursive_lock_unlock(recursive_lock *lock);
 extern int32 recursive_lock_get_recursion(recursive_lock *lock);
 
diff --git a/src/system/kernel/lock.cpp b/src/system/kernel/lock.cpp
index 6a8371dd11..f8165249f0 100644
--- a/src/system/kernel/lock.cpp
+++ b/src/system/kernel/lock.cpp
@@ -92,12 +92,37 @@ recursive_lock_lock(recursive_lock *lock)
 {
 	thread_id thread = thread_get_current_thread_id();
 
+	if (!kernel_startup && !are_interrupts_enabled()) {
+		panic("recursive_lock_lock: called with interrupts disabled for lock "
+			"%p (\"%s\")\n", lock, lock->lock.name);
+	}
+
+	if (thread != RECURSIVE_LOCK_HOLDER(lock)) {
+		mutex_lock(&lock->lock);
+#ifndef KDEBUG
+		lock->holder = thread;
+#endif
+	}
+
+	lock->recursion++;
+	return B_OK;
+}
+
+
+status_t
+recursive_lock_trylock(recursive_lock *lock)
+{
+	thread_id thread = thread_get_current_thread_id();
+
 	if (!kernel_startup && !are_interrupts_enabled())
 		panic("recursive_lock_lock: called with interrupts disabled for lock "
 			"%p (\"%s\")\n", lock, lock->lock.name);
 
 	if (thread != RECURSIVE_LOCK_HOLDER(lock)) {
-		mutex_lock(&lock->lock);
+		status_t status = mutex_trylock(&lock->lock);
+		if (status != B_OK)
+			return status;
+
 #ifndef KDEBUG
 		lock->holder = thread;
 #endif
diff --git a/src/tools/fs_shell/lock.cpp b/src/tools/fs_shell/lock.cpp
index 7e223f01dd..ae57764158 100644
--- a/src/tools/fs_shell/lock.cpp
+++ b/src/tools/fs_shell/lock.cpp
@@ -71,6 +71,24 @@ fssh_recursive_lock_lock(fssh_recursive_lock *lock)
 }
 
 
+extern "C" fssh_status_t
+fssh_recursive_lock_trylock(fssh_recursive_lock *lock)
+{
+	fssh_thread_id thread = fssh_find_thread(NULL);
+
+	if (thread != lock->holder) {
+		fssh_status_t status = fssh_acquire_sem_etc(lock->sem, 1,
+			FSSH_B_RELATIVE_TIMEOUT, 0);
+		if (status < FSSH_B_OK)
+			return status;
+
+		lock->holder = thread;
+	}
+	lock->recursion++;
+	return FSSH_B_OK;
+}
+
+
 extern "C" void
 fssh_recursive_lock_unlock(fssh_recursive_lock *lock)
 {