From 8f0530c50755cbd860c92039ac22396d6ed56a24 Mon Sep 17 00:00:00 2001
From: Nye Liu <nyet@nyet.org>
Date: Fri, 11 Sep 2015 10:42:01 -0700
Subject: [PATCH] Add retry to CondVarBase wait(), make sure Stopwatch is
 started on construction (Issue #4735)

* ArchMultithreadPosix::waitCondVar() returns every 100ms, so retry until we
  hit timeout.

* Stopwatch constructor should be called with "false" (not "true") to make sure
  Stopwatch is actually running when instantiated.
---
 src/lib/client/Client.cpp              |  9 +++++++--
 src/lib/mt/CondVar.cpp                 | 14 ++++++++------
 src/lib/platform/XWindowsClipboard.cpp |  5 +++--
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/lib/client/Client.cpp b/src/lib/client/Client.cpp
index 41b1df24..33048807 100644
--- a/src/lib/client/Client.cpp
+++ b/src/lib/client/Client.cpp
@@ -283,13 +283,15 @@ Client::leave()
 									&Client::sendClipboardThread,
 									NULL));
 	// Bug #4735 - we can't leave() until fillClipboard()s all finish
-	Stopwatch timer(true);
+	Stopwatch timer(false);
 	m_mutex->lock();
 	while (!m_condData) {
 		if (!m_condVar->wait(timer, 0.5)) {
-			LOG((CLOG_DEBUG "timed out waiting for clipboard fill"));
+			LOG((CLOG_WARN "timed out %fs waiting for clipboard fill",
+				(double) timer.getTime()));
 			break;
 		}
+		LOG((CLOG_DEBUG1 "leave %fs elapsed", (double) timer.getTime()));
 	}
 	m_mutex->unlock();
 
@@ -789,6 +791,7 @@ Client::onFileRecieveCompleted()
 void
 Client::sendClipboardThread(void * data)
 {
+	Stopwatch timer(false);
 	Clipboard clipboard[kClipboardEnd];
 	// fill clipboards that we own and that have changed
 	for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
@@ -796,6 +799,7 @@ Client::sendClipboardThread(void * data)
 			fillClipboard(id, &clipboard[id]);
 		}
 	}
+	LOG((CLOG_DEBUG1 "fill took %fs, signaling", (double) timer.getTime()));
 
 	// signal that fill is done
 	m_mutex->lock();
@@ -811,6 +815,7 @@ Client::sendClipboardThread(void * data)
 	}
 
 	m_sendClipboardThread = NULL;
+	LOG((CLOG_DEBUG1 "send took %fs", (double) timer.getTime()));
 }
 
 void
diff --git a/src/lib/mt/CondVar.cpp b/src/lib/mt/CondVar.cpp
index 2ec18e46..caa12210 100644
--- a/src/lib/mt/CondVar.cpp
+++ b/src/lib/mt/CondVar.cpp
@@ -63,13 +63,15 @@ CondVarBase::broadcast()
 bool
 CondVarBase::wait(Stopwatch& timer, double timeout) const
 {
-	// check timeout against timer
-	if (timeout >= 0.0) {
-		timeout -= timer.getTime();
-		if (timeout < 0.0)
-			return false;
+	double remain = timeout-timer.getTime();
+	// Some ARCH wait()s return prematurely, retry until really timed out
+	// In particular, ArchMultithreadPosix::waitCondVar() returns every 100ms
+	while (remain >= 0.0) {
+		if (wait(remain))
+			return true;
+		remain = timeout - timer.getTime();
 	}
-	return wait(timeout);
+	return false;
 }
 
 bool
diff --git a/src/lib/platform/XWindowsClipboard.cpp b/src/lib/platform/XWindowsClipboard.cpp
index 7db899f1..ef587739 100644
--- a/src/lib/platform/XWindowsClipboard.cpp
+++ b/src/lib/platform/XWindowsClipboard.cpp
@@ -513,6 +513,7 @@ XWindowsClipboard::icccmFillCache()
 		LOG((CLOG_DEBUG1 "selection doesn't support TARGETS"));
 		data = "";
 		XWindowsUtil::appendAtomData(data, XA_STRING);
+		// return; // NTL
 	}
 
 	XWindowsUtil::convertAtomProperty(data);
@@ -1317,7 +1318,7 @@ XWindowsClipboard::CICCCMGetClipboard::readClipboard(Display* display,
 	// by badly behaved selection owners.
 	XEvent xevent;
 	std::vector<XEvent> events;
-	Stopwatch timeout(true);
+	Stopwatch timeout(false);	// timer not stopped, not triggered
 	static const double s_timeout = 0.25;	// FIXME -- is this too short?
 	bool noWait = false;
 	while (!m_done && !m_failed) {
@@ -1361,7 +1362,7 @@ XWindowsClipboard::CICCCMGetClipboard::readClipboard(Display* display,
 	XSelectInput(display, m_requestor, attr.your_event_mask);
 
 	// return success or failure
-	LOG((CLOG_DEBUG1 "request %s", m_failed ? "failed" : "succeeded"));
+	LOG((CLOG_DEBUG1 "request %s after %fs", m_failed ? "failed" : "succeeded", timeout.getTime()));
 	return !m_failed;
 }