From bb85ec442dd7b5b0966d73bc6b868d33bb03e5e9 Mon Sep 17 00:00:00 2001
From: Alexander Shalamov <alexander.shalamov@mapbox.com>
Date: Fri, 31 Jan 2020 17:06:37 +0200
Subject: [core] Add hooks for setting experimental thread priorities for mbgl
 threads

---
 include/mbgl/util/thread.hpp                       | 38 +++++++++++++---------
 next/CMakeLists.txt                                |  1 +
 platform/android/src/asset_manager_file_source.cpp | 11 ++++---
 .../default/src/mbgl/storage/asset_file_source.cpp |  5 +--
 .../src/mbgl/storage/database_file_source.cpp      |  7 +++-
 .../default/src/mbgl/storage/local_file_source.cpp |  5 +--
 .../src/mbgl/storage/main_resource_loader.cpp      |  8 ++++-
 .../src/mbgl/storage/online_file_source.cpp        | 11 ++++---
 src/core-files.json                                |  3 ++
 src/mbgl/util/thread.cpp                           | 19 +++++++++++
 src/mbgl/util/thread_pool.cpp                      | 11 +++++--
 11 files changed, 88 insertions(+), 31 deletions(-)
 create mode 100644 src/mbgl/util/thread.cpp

diff --git a/include/mbgl/util/thread.hpp b/include/mbgl/util/thread.hpp
index ab0403e44e..4bc948fdbd 100644
--- a/include/mbgl/util/thread.hpp
+++ b/include/mbgl/util/thread.hpp
@@ -3,10 +3,10 @@
 #include <mbgl/actor/actor.hpp>
 #include <mbgl/actor/mailbox.hpp>
 #include <mbgl/actor/scheduler.hpp>
+#include <mbgl/platform/thread.hpp>
 #include <mbgl/util/platform.hpp>
 #include <mbgl/util/run_loop.hpp>
 #include <mbgl/util/util.hpp>
-#include <mbgl/platform/thread.hpp>
 
 #include <cassert>
 #include <future>
@@ -37,25 +37,20 @@ namespace util {
 // - A `RunLoop` is created for the `Object` thread.
 // - `Object` can use `Timer` and do asynchronous I/O, like wait for sockets events.
 //
-template<class Object>
+template <typename Object>
 class Thread {
 public:
-    template <class... Args>
-    Thread(const std::string& name, Args&&... args) {
-
+    template <typename TupleArgs>
+    Thread(std::function<void()> prioritySetter_, const std::string& name, TupleArgs&& args) {
         std::promise<void> running_;
         running = running_.get_future();
-
-        auto capturedArgs = std::make_tuple(std::forward<Args>(args)...);
-
-        thread = std::thread([
-            this,
-            name,
-            capturedArgs = std::move(capturedArgs),
-            runningPromise = std::move(running_)
-        ] () mutable {
+        thread = std::thread([this,
+                              name,
+                              capturedArgs = std::forward<TupleArgs>(args),
+                              runningPromise = std::move(running_),
+                              prioritySetter = std::move(prioritySetter_)]() mutable {
             platform::setCurrentThreadName(name);
-            platform::makeThreadLowPriority();
+            if (prioritySetter) prioritySetter();
             platform::attachThread();
 
             // narrowing the scope to release the Object before we detach the thread
@@ -77,6 +72,14 @@ public:
         });
     }
 
+    template <typename... Args>
+    Thread(const std::string& name, Args&&... args)
+        : Thread([] { platform::makeThreadLowPriority(); }, name, std::make_tuple(std::forward<Args>(args)...)) {}
+
+    template <typename... Args>
+    Thread(std::function<void()> prioritySetter, const std::string& name, Args&&... args)
+        : Thread(std::move(prioritySetter), name, std::make_tuple(std::forward<Args>(args)...)) {}
+
     ~Thread() {
         if (paused) {
             resume();
@@ -158,5 +161,10 @@ private:
     util::RunLoop* loop = nullptr;
 };
 
+// Returns function, that once invoked, will set a thread priority for
+// a thread `threadType` based on a setting provided by corresponding
+// Settings' platform::EXPERIMENTAL_THREAD_PRIORITY_* value.
+std::function<void()> makeThreadPrioritySetter(std::string threadType);
+
 } // namespace util
 } // namespace mbgl
diff --git a/next/CMakeLists.txt b/next/CMakeLists.txt
index e956f3e5db..50b1f62ccc 100644
--- a/next/CMakeLists.txt
+++ b/next/CMakeLists.txt
@@ -780,6 +780,7 @@ add_library(
     ${MBGL_ROOT}/src/mbgl/util/stopwatch.cpp
     ${MBGL_ROOT}/src/mbgl/util/stopwatch.hpp
     ${MBGL_ROOT}/src/mbgl/util/string.cpp
+    ${MBGL_ROOT}/src/mbgl/util/thread.cpp
     ${MBGL_ROOT}/src/mbgl/util/thread_local.hpp
     ${MBGL_ROOT}/src/mbgl/util/thread_pool.cpp
     ${MBGL_ROOT}/src/mbgl/util/thread_pool.hpp
diff --git a/platform/android/src/asset_manager_file_source.cpp b/platform/android/src/asset_manager_file_source.cpp
index 73ecec2b05..a8045a2b96 100644
--- a/platform/android/src/asset_manager_file_source.cpp
+++ b/platform/android/src/asset_manager_file_source.cpp
@@ -1,5 +1,6 @@
 #include "asset_manager_file_source.hpp"
 
+#include <mbgl/platform/settings.hpp>
 #include <mbgl/storage/file_source_request.hpp>
 #include <mbgl/storage/resource.hpp>
 #include <mbgl/storage/response.hpp>
@@ -39,11 +40,13 @@ private:
     AAssetManager* assetManager;
 };
 
-AssetManagerFileSource::AssetManagerFileSource(jni::JNIEnv& env, const jni::Object<android::AssetManager>& assetManager_)
+AssetManagerFileSource::AssetManagerFileSource(jni::JNIEnv& env,
+                                               const jni::Object<android::AssetManager>& assetManager_)
     : assetManager(jni::NewGlobal(env, assetManager_)),
-      impl(std::make_unique<util::Thread<Impl>>("AssetManagerFileSource",
-          AAssetManager_fromJava(&env, jni::Unwrap(assetManager.get())))) {
-}
+      impl(std::make_unique<util::Thread<Impl>>(
+          util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_FILE),
+          "AssetManagerFileSource",
+          AAssetManager_fromJava(&env, jni::Unwrap(assetManager.get())))) {}
 
 AssetManagerFileSource::~AssetManagerFileSource() = default;
 
diff --git a/platform/default/src/mbgl/storage/asset_file_source.cpp b/platform/default/src/mbgl/storage/asset_file_source.cpp
index 7abd609b19..a9ede06508 100644
--- a/platform/default/src/mbgl/storage/asset_file_source.cpp
+++ b/platform/default/src/mbgl/storage/asset_file_source.cpp
@@ -1,3 +1,4 @@
+#include <mbgl/platform/settings.hpp>
 #include <mbgl/storage/asset_file_source.hpp>
 #include <mbgl/storage/file_source_request.hpp>
 #include <mbgl/storage/local_file_request.hpp>
@@ -42,8 +43,8 @@ private:
 };
 
 AssetFileSource::AssetFileSource(const std::string& root)
-    : impl(std::make_unique<util::Thread<Impl>>("AssetFileSource", root)) {
-}
+    : impl(std::make_unique<util::Thread<Impl>>(
+          util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_FILE), "AssetFileSource", root)) {}
 
 AssetFileSource::~AssetFileSource() = default;
 
diff --git a/platform/default/src/mbgl/storage/database_file_source.cpp b/platform/default/src/mbgl/storage/database_file_source.cpp
index b46693849a..f0b4849cb0 100644
--- a/platform/default/src/mbgl/storage/database_file_source.cpp
+++ b/platform/default/src/mbgl/storage/database_file_source.cpp
@@ -1,3 +1,4 @@
+#include <mbgl/platform/settings.hpp>
 #include <mbgl/storage/database_file_source.hpp>
 #include <mbgl/storage/file_source_manager.hpp>
 #include <mbgl/storage/file_source_request.hpp>
@@ -7,6 +8,7 @@
 #include <mbgl/storage/response.hpp>
 #include <mbgl/util/constants.hpp>
 #include <mbgl/util/logging.hpp>
+#include <mbgl/util/platform.hpp>
 #include <mbgl/util/thread.hpp>
 
 namespace mbgl {
@@ -149,7 +151,10 @@ class DatabaseFileSource::Impl {
 public:
     Impl(std::shared_ptr<FileSource> onlineFileSource, const std::string& cachePath)
         : thread(std::make_unique<util::Thread<DatabaseFileSourceThread>>(
-              "DatabaseFileSource", std::move(onlineFileSource), cachePath)) {}
+              util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_DATABASE),
+              "DatabaseFileSource",
+              std::move(onlineFileSource),
+              cachePath)) {}
 
     ActorRef<DatabaseFileSourceThread> actor() const { return thread->actor(); }
 
diff --git a/platform/default/src/mbgl/storage/local_file_source.cpp b/platform/default/src/mbgl/storage/local_file_source.cpp
index 54f12baf79..5009146c8e 100644
--- a/platform/default/src/mbgl/storage/local_file_source.cpp
+++ b/platform/default/src/mbgl/storage/local_file_source.cpp
@@ -1,3 +1,4 @@
+#include <mbgl/platform/settings.hpp>
 #include <mbgl/storage/file_source_request.hpp>
 #include <mbgl/storage/local_file_request.hpp>
 #include <mbgl/storage/local_file_source.hpp>
@@ -36,8 +37,8 @@ public:
 };
 
 LocalFileSource::LocalFileSource()
-    : impl(std::make_unique<util::Thread<Impl>>("LocalFileSource")) {
-}
+    : impl(std::make_unique<util::Thread<Impl>>(
+          util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_FILE), "LocalFileSource")) {}
 
 LocalFileSource::~LocalFileSource() = default;
 
diff --git a/platform/default/src/mbgl/storage/main_resource_loader.cpp b/platform/default/src/mbgl/storage/main_resource_loader.cpp
index 91ae0a1d71..fb69a8c4f4 100644
--- a/platform/default/src/mbgl/storage/main_resource_loader.cpp
+++ b/platform/default/src/mbgl/storage/main_resource_loader.cpp
@@ -1,5 +1,6 @@
 #include <mbgl/actor/actor.hpp>
 #include <mbgl/actor/scheduler.hpp>
+#include <mbgl/platform/settings.hpp>
 #include <mbgl/storage/file_source_manager.hpp>
 #include <mbgl/storage/file_source_request.hpp>
 #include <mbgl/storage/main_resource_loader.hpp>
@@ -131,7 +132,12 @@ public:
           onlineFileSource(std::move(onlineFileSource_)),
           supportsCacheOnlyRequests_(bool(databaseFileSource)),
           thread(std::make_unique<util::Thread<MainResourceLoaderThread>>(
-              "ResourceLoaderThread", assetFileSource, databaseFileSource, localFileSource, onlineFileSource)) {}
+              util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_WORKER),
+              "ResourceLoaderThread",
+              assetFileSource,
+              databaseFileSource,
+              localFileSource,
+              onlineFileSource)) {}
 
     std::unique_ptr<AsyncRequest> request(const Resource& resource, Callback callback) {
         auto req = std::make_unique<FileSourceRequest>(std::move(callback));
diff --git a/platform/default/src/mbgl/storage/online_file_source.cpp b/platform/default/src/mbgl/storage/online_file_source.cpp
index 0f5b438e1d..37b1f7ca8e 100644
--- a/platform/default/src/mbgl/storage/online_file_source.cpp
+++ b/platform/default/src/mbgl/storage/online_file_source.cpp
@@ -1,8 +1,8 @@
-#include <mbgl/storage/online_file_source.hpp>
+#include <mbgl/platform/settings.hpp>
+#include <mbgl/storage/file_source_request.hpp>
 #include <mbgl/storage/http_file_source.hpp>
 #include <mbgl/storage/network_status.hpp>
-
-#include <mbgl/storage/file_source_request.hpp>
+#include <mbgl/storage/online_file_source.hpp>
 #include <mbgl/storage/resource_transform.hpp>
 #include <mbgl/storage/response.hpp>
 #include <mbgl/util/logging.hpp>
@@ -15,6 +15,7 @@
 #include <mbgl/util/http_timeout.hpp>
 #include <mbgl/util/mapbox.hpp>
 #include <mbgl/util/noncopyable.hpp>
+#include <mbgl/util/platform.hpp>
 #include <mbgl/util/run_loop.hpp>
 #include <mbgl/util/thread.hpp>
 #include <mbgl/util/timer.hpp>
@@ -293,7 +294,9 @@ private:
 
 class OnlineFileSource::Impl {
 public:
-    Impl() : thread(std::make_unique<util::Thread<OnlineFileSourceThread>>("OnlineFileSource")) {}
+    Impl()
+        : thread(std::make_unique<util::Thread<OnlineFileSourceThread>>(
+              util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_NETWORK), "OnlineFileSource")) {}
 
     std::unique_ptr<AsyncRequest> request(Callback callback, Resource res) {
         auto req = std::make_unique<FileSourceRequest>(std::move(callback));
diff --git a/src/core-files.json b/src/core-files.json
index 3c0e128b18..fe68df16bf 100644
--- a/src/core-files.json
+++ b/src/core-files.json
@@ -62,6 +62,7 @@
         "src/mbgl/map/transform_state.cpp",
         "src/mbgl/math/log2.cpp",
         "src/mbgl/platform/gl_functions.cpp",
+        "src/mbgl/platform/settings.cpp",
         "src/mbgl/programs/background_program.cpp",
         "src/mbgl/programs/circle_program.cpp",
         "src/mbgl/programs/clipping_mask_program.cpp",
@@ -316,6 +317,7 @@
         "src/mbgl/util/rapidjson.cpp",
         "src/mbgl/util/stopwatch.cpp",
         "src/mbgl/util/string.cpp",
+        "src/mbgl/util/thread.cpp",
         "src/mbgl/util/thread_pool.cpp",
         "src/mbgl/util/tile_cover.cpp",
         "src/mbgl/util/tile_cover_impl.cpp",
@@ -369,6 +371,7 @@
         "mbgl/math/minmax.hpp": "include/mbgl/math/minmax.hpp",
         "mbgl/math/wrap.hpp": "include/mbgl/math/wrap.hpp",
         "mbgl/platform/gl_functions.hpp": "include/mbgl/platform/gl_functions.hpp",
+        "mbgl/platform/settings.hpp": "include/mbgl/platform/settings.hpp",
         "mbgl/platform/thread.hpp": "include/mbgl/platform/thread.hpp",
         "mbgl/renderer/query.hpp": "include/mbgl/renderer/query.hpp",
         "mbgl/renderer/renderer.hpp": "include/mbgl/renderer/renderer.hpp",
diff --git a/src/mbgl/util/thread.cpp b/src/mbgl/util/thread.cpp
new file mode 100644
index 0000000000..016d23a928
--- /dev/null
+++ b/src/mbgl/util/thread.cpp
@@ -0,0 +1,19 @@
+#include <functional>
+#include <mbgl/platform/settings.hpp>
+#include <mbgl/util/platform.hpp>
+
+namespace mbgl {
+namespace util {
+std::function<void()> makeThreadPrioritySetter(std::string threadType_) {
+    return [threadType = std::move(threadType_)] {
+        auto& settings = platform::Settings::getInstance();
+        auto value = settings.get(threadType);
+        if (auto* priority = value.getDouble()) {
+            platform::setCurrentThreadPriority(*priority);
+        } else {
+            platform::makeThreadLowPriority();
+        }
+    };
+}
+} // namespace util
+} // namespace mbgl
diff --git a/src/mbgl/util/thread_pool.cpp b/src/mbgl/util/thread_pool.cpp
index 040e996dd4..e1c18a45b5 100644
--- a/src/mbgl/util/thread_pool.cpp
+++ b/src/mbgl/util/thread_pool.cpp
@@ -1,8 +1,9 @@
 #include <mbgl/util/thread_pool.hpp>
 
+#include <mbgl/platform/settings.hpp>
+#include <mbgl/platform/thread.hpp>
 #include <mbgl/util/platform.hpp>
 #include <mbgl/util/string.hpp>
-#include <mbgl/platform/thread.hpp>
 
 namespace mbgl {
 
@@ -17,7 +18,13 @@ void ThreadedSchedulerBase::terminate() {
 }
 
 std::thread ThreadedSchedulerBase::makeSchedulerThread(size_t index) {
-    return std::thread([this, index]() {
+    return std::thread([this, index] {
+        auto& settings = platform::Settings::getInstance();
+        auto value = settings.get(platform::EXPERIMENTAL_THREAD_PRIORITY_WORKER);
+        if (auto* priority = value.getDouble()) {
+            platform::setCurrentThreadPriority(*priority);
+        }
+
         platform::setCurrentThreadName(std::string{"Worker "} + util::toString(index + 1));
         platform::attachThread();
 
-- 
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