From 58e012d1e37e1272d43c9ff0f56c9b236dd1d7f1 Mon Sep 17 00:00:00 2001
From: Glenn Kasten <gkasten@google.com>
Date: Thu, 23 Jun 2011 12:55:29 -0700
Subject: [PATCH] Add Thread::join

This new API will be used by applications that previously used the
lower-level pthread APIs (including pthread_join).  Centralizing on the
Thread class instead of pthread will permit additional functionality to
be added later in only one location.

Change-Id: I8460169ac9c61ac9f85752405ed54c94651058d7
---
 include/utils/threads.h |  4 ++++
 libs/utils/Threads.cpp  | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/utils/threads.h b/include/utils/threads.h
index 0bd69cf37..432805e2c 100644
--- a/include/utils/threads.h
+++ b/include/utils/threads.h
@@ -510,6 +510,10 @@ public:
     // that case.
             status_t    requestExitAndWait();
 
+    // Wait until this object's thread exits. Returns immediately if not yet running.
+    // Do not call from this object's thread; will return WOULD_BLOCK in that case.
+            status_t    join();
+
 protected:
     // exitPending() returns true if requestExit() has been called.
             bool        exitPending() const;
diff --git a/libs/utils/Threads.cpp b/libs/utils/Threads.cpp
index 15bb1d226..48ce5d125 100644
--- a/libs/utils/Threads.cpp
+++ b/libs/utils/Threads.cpp
@@ -842,6 +842,25 @@ status_t Thread::requestExitAndWait()
     return mStatus;
 }
 
+status_t Thread::join()
+{
+    Mutex::Autolock _l(mLock);
+    if (mThread == getThreadId()) {
+        LOGW(
+        "Thread (this=%p): don't call join() from this "
+        "Thread object's thread. It's a guaranteed deadlock!",
+        this);
+
+        return WOULD_BLOCK;
+    }
+
+    while (mRunning == true) {
+        mThreadExitedCondition.wait(mLock);
+    }
+
+    return mStatus;
+}
+
 bool Thread::exitPending() const
 {
     Mutex::Autolock _l(mLock);