From ecd68a6057f966c26e3389bfd2064bb6af1dc80c Mon Sep 17 00:00:00 2001
From: casey langen <casey.langen@gmail.com>
Date: Tue, 6 Oct 2020 21:43:45 -0700
Subject: [PATCH] IQuery::Synchronous support in RemoteLibrary.

---
 src/core/library/RemoteLibrary.cpp | 35 ++++++++++++++++--------------
 src/core/library/RemoteLibrary.h   | 10 ++++-----
 2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/src/core/library/RemoteLibrary.cpp b/src/core/library/RemoteLibrary.cpp
index 3e5d9ed8d..4b8bb13bc 100644
--- a/src/core/library/RemoteLibrary.cpp
+++ b/src/core/library/RemoteLibrary.cpp
@@ -115,7 +115,7 @@ void RemoteLibrary::Close() {
     std::thread* thread = nullptr;
 
     {
-        std::unique_lock<std::recursive_mutex> lock(this->mutex);
+        std::unique_lock<std::recursive_mutex> lock(this->queueMutex);
         if (this->thread) {
             thread = this->thread;
             this->thread = nullptr;
@@ -126,6 +126,7 @@ void RemoteLibrary::Close() {
 
     if (thread) {
         this->queueCondition.notify_all();
+        this->syncQueryCondition.notify_all();
         thread->join();
         delete thread;
     }
@@ -144,20 +145,20 @@ int RemoteLibrary::Enqueue(QueryPtr query, unsigned int options, Callback callba
     auto serializableQuery = std::dynamic_pointer_cast<ISerializableQuery>(query);
 
     if (serializableQuery) {
-        std::unique_lock<std::recursive_mutex> lock(this->mutex);
-
-        if (this->exit) { /* closed */
-            return -1;
-        }
-
         auto context = std::make_shared<QueryContext>();
         context->query = serializableQuery;
         context->callback = callback;
 
         if (options & ILibrary::QuerySynchronous) {
-            this->RunQuery(context, false); /* false = do not notify via QueryCompleted */
+            this->RunQuery(context); /* false = do not notify via QueryCompleted */
+            std::unique_lock<std::recursive_mutex> lock(this->queueMutex);
+            while (!this->exit && context->query->GetStatus() == IQuery::Idle) {
+                this->syncQueryCondition.wait(lock);
+            }
         }
         else {
+            std::unique_lock<std::recursive_mutex> lock(this->queueMutex);
+            if (this->exit) { return -1; }
             queryQueue.push_back(context);
             queueCondition.notify_all();
         }
@@ -169,7 +170,7 @@ int RemoteLibrary::Enqueue(QueryPtr query, unsigned int options, Callback callba
 }
 
 RemoteLibrary::QueryContextPtr RemoteLibrary::GetNextQuery() {
-    std::unique_lock<std::recursive_mutex> lock(this->mutex);
+    std::unique_lock<std::recursive_mutex> lock(this->queueMutex);
     while (!this->queryQueue.size() && !this->exit) {
         this->queueCondition.wait(lock);
     }
@@ -214,7 +215,7 @@ void RemoteLibrary::OnQueryCompleted(const std::string& messageId, Query query)
     QueryContextPtr context;
 
     {
-        std::unique_lock<std::recursive_mutex> lock(this->mutex);
+        std::unique_lock<std::recursive_mutex> lock(this->queueMutex);
         context = queriesInFlight[messageId];
         queriesInFlight.erase(messageId);
     }
@@ -222,17 +223,19 @@ void RemoteLibrary::OnQueryCompleted(const std::string& messageId, Query query)
     if (context) {
         this->OnQueryCompleted(context);
     }
+
+    this->syncQueryCondition.notify_all();
 }
 
-void RemoteLibrary::RunQuery(QueryContextPtr context, bool notify) {
+void RemoteLibrary::RunQuery(QueryContextPtr context) {
 #if 0
-    this->RunQueryOnLoopback(context, notify);
+    this->RunQueryOnLoopback(context);
 #else
-    this->RunQueryOnWebSocketClient(context, notify);
+    this->RunQueryOnWebSocketClient(context);
 #endif
 }
 
-void RemoteLibrary::RunQueryOnLoopback(QueryContextPtr context, bool notify) {
+void RemoteLibrary::RunQueryOnLoopback(QueryContextPtr context) {
     if (context) {
         /* do everything via loopback to the local library for testing. we do, however,
         go through the motions by serializing the inbound query to a string, then
@@ -263,9 +266,9 @@ void RemoteLibrary::RunQueryOnLoopback(QueryContextPtr context, bool notify) {
     }
 }
 
-void RemoteLibrary::RunQueryOnWebSocketClient(QueryContextPtr context, bool notify) {
+void RemoteLibrary::RunQueryOnWebSocketClient(QueryContextPtr context) {
     if (context->query) {
-        std::unique_lock<std::recursive_mutex> lock(this->mutex);
+        std::unique_lock<std::recursive_mutex> lock(this->queueMutex);
         const std::string messageId = wsc.EnqueueQuery(context->query);
         if (messageId.size()) {
             queriesInFlight[messageId] = context;
diff --git a/src/core/library/RemoteLibrary.h b/src/core/library/RemoteLibrary.h
index a842d2d0b..c65e9e3bf 100644
--- a/src/core/library/RemoteLibrary.h
+++ b/src/core/library/RemoteLibrary.h
@@ -100,9 +100,9 @@ namespace musik { namespace core { namespace library {
 
             RemoteLibrary(std::string name, int id); /* ctor */
 
-            void RunQuery(QueryContextPtr context, bool notify = true);
-            void RunQueryOnLoopback(QueryContextPtr context, bool notify);
-            void RunQueryOnWebSocketClient(QueryContextPtr context, bool notify);
+            void RunQuery(QueryContextPtr context);
+            void RunQueryOnLoopback(QueryContextPtr context);
+            void RunQueryOnWebSocketClient(QueryContextPtr context);
 
             void OnQueryCompleted(const std::string& messageId, Query query);
             void OnQueryCompleted(QueryContextPtr context);
@@ -123,8 +123,8 @@ namespace musik { namespace core { namespace library {
             std::unordered_map<std::string, QueryContextPtr> queriesInFlight;
 
             std::thread* thread;
-            std::condition_variable_any queueCondition;
-            std::recursive_mutex mutex;
+            std::condition_variable_any queueCondition, syncQueryCondition;
+            std::recursive_mutex queueMutex;
             std::atomic<bool> exit;
 
     };