[core] Add platform::setCurrentThreadPriority(double)

include/mbgl/util/platform.hpp

@@ -22,5 +22,9 @@ void setCurrentThreadName(const std::string& name);
 // Makes the current thread low priority.
 void makeThreadLowPriority();
 
+// Sets priority of a current thread. Platform implementation
+// must validate provided value.
+void setCurrentThreadPriority(double priority);
+
 } // namespace platform
 } // namespace mbgl

platform/android/src/thread.cpp

@@ -40,6 +40,14 @@ void makeThreadLowPriority() {
     setpriority(PRIO_PROCESS, 0, 19);
 }
 
+void setCurrentThreadPriority(double priority) {
+    if (priority < -20 || priority > 19) {
+        Log::Warning(Event::General, "Couldn't set thread priority");
+        return;
+    }
+    setpriority(PRIO_PROCESS, 0, int(priority));
+}
+
 void attachThread() {
     using namespace android;
     assert(env == nullptr);

platform/darwin/src/nsthread.mm

@@ -1,5 +1,6 @@
 #import <Foundation/Foundation.h>
 
+#include <mbgl/util/logging.hpp>
 #include <mbgl/util/platform.hpp>
 #include <mbgl/platform/thread.hpp>
 
@@ -24,6 +25,15 @@ void makeThreadLowPriority() {
     [[NSThread currentThread] setThreadPriority:0.0];
 }
 
+void setCurrentThreadPriority(double priority) {
+    if (priority > 1.0 || priority < 0.0) {
+        Log::Warning(Event::General, "Invalid thread priority was provided");
+        return;
+    }
+
+    [[NSThread currentThread] setThreadPriority:priority];
+}
+
 void attachThread() {
 }
 

platform/default/src/mbgl/util/thread.cpp

@@ -6,6 +6,7 @@
 
 #include <pthread.h>
 #include <sched.h>
+#include <sys/resource.h>
 
 namespace mbgl {
 namespace platform {
@@ -40,11 +41,23 @@ void makeThreadLowPriority() {
 #endif
 }
 
-void attachThread() {
-}
+void setCurrentThreadPriority(double priority) {
+    if (setpriority(PRIO_PROCESS, 0, int(priority)) < 0) {
+        Log::Warning(Event::General, "Couldn't set thread priority");
+    }
 
-void detachThread() {
+#ifdef SCHED_OTHER
+    struct sched_param param;
+    param.sched_priority = 0;
+    if (sched_setscheduler(0, SCHED_OTHER, &param) != 0) {
+        Log::Warning(Event::General, "Couldn't set thread scheduling policy");
+    }
+#endif
 }
 
+void attachThread() {}
+
+void detachThread() {}
+
 } // namespace platform
 } // namespace mbgl

platform/qt/src/thread.cpp

@@ -16,6 +16,8 @@ void setCurrentThreadName(const std::string&) {
 void makeThreadLowPriority() {
 }
 
+void setCurrentThreadPriority(double) {}
+
 void attachThread() {
 }