Added initializer function for static android builds.

Author: ras0219-msft

Build/Common.Build.settings

@@ -114,7 +114,7 @@
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <ClCompile>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>WIN32;_DEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <GenerateDebugInformation>true</GenerateDebugInformation>
@@ -132,7 +132,7 @@
 
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'">
     <ClCompile>
-      <PreprocessorDefinitions>WIN32;_DEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <GenerateDebugInformation>true</GenerateDebugInformation>
@@ -150,7 +150,7 @@
 
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM'">
     <ClCompile>
-      <PreprocessorDefinitions>WIN32;NDEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>NDEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <GenerateDebugInformation>true</GenerateDebugInformation>
@@ -159,7 +159,7 @@
 
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <ClCompile>
-      <PreprocessorDefinitions>WIN32;NDEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>NDEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <GenerateDebugInformation>true</GenerateDebugInformation>

Release/include/pplx/pplxtasks.h

@@ -55,6 +55,11 @@ namespace Concurrency {
 
 #include "pplx/pplx.h"
 
+#if defined(__ANDROID__)
+#include <jni.h>
+void cpprest_init(JavaVM*);
+#endif
+
 // Cannot build using a compiler that is older than dev10 SP1
 #if defined(_MSC_VER)
 #if _MSC_FULL_VER < 160040219 /*IFSTRIP=IGN*/

Release/include/pplx/threadpool.h

@@ -74,12 +74,14 @@ class threadpool
         for (size_t i = 0; i < n; i++)
             add_thread();
     }
-
+#if defined(__ANDROID__)
+    static threadpool& shared_instance();
+#else
     static threadpool& shared_instance()
     {
         return s_shared;
     }
-
+#endif
     ~threadpool()
     {
         m_service.stop();
@@ -105,7 +107,9 @@ class threadpool
 private:
     struct _cancel_thread { };
 
+#if !defined(__ANDROID__)
     static threadpool s_shared;
+#endif
 
     void add_thread()
     {
@@ -130,11 +134,6 @@ class threadpool
     static void* thread_start(void *arg)
     {
 #if (defined(ANDROID) || defined(__ANDROID__))
-        // Spinlock on the JVM calling JNI_OnLoad()
-        while (JVM == nullptr)
-        {
-            pplx::details::platform::YieldExecution();
-        }
         // Calling get_jvm_env() here forces the thread to be attached.
         get_jvm_env();
         pthread_cleanup_push(detach_from_java, nullptr);

Release/src/pplx/threadpool.cpp

@@ -18,21 +18,29 @@
 **/
 #include "stdafx.h"
 
+#if defined(__ANDROID__)
+#include <android/log.h>
+#include <jni.h>
+#endif
+
 namespace crossplat
 {
-// initialize the static shared threadpool
-threadpool threadpool::s_shared(40);
-
 #if (defined(ANDROID) || defined(__ANDROID__))
 // This pointer will be 0-initialized by default (at load time).
 std::atomic<JavaVM*> JVM;
 
-JNIEnv* get_jvm_env()
+static void abort_if_no_jvm()
 {
     if (JVM == nullptr)
     {
-        throw std::runtime_error("Could not contact JVM");
+        __android_log_print(ANDROID_LOG_ERROR, "CPPRESTSDK", "%s", "The CppREST SDK must be initialized before first use on android: https://casablanca.codeplex.com/wikipage?title=Use%20on%20Android");
+        std::abort();
     }
+}
+
+JNIEnv* get_jvm_env()
+{
+    abort_if_no_jvm();
     JNIEnv* env = nullptr;
     auto result = JVM.load()->AttachCurrentThread(&env, nullptr);
     if (result != JNI_OK)
@@ -43,20 +51,25 @@ JNIEnv* get_jvm_env()
     return env;
 }
 
+threadpool& threadpool::shared_instance()
+{
+    abort_if_no_jvm();
+    static threadpool s_shared(40);
+    return s_shared;
+}
+
+#else
+
+// initialize the static shared threadpool
+threadpool threadpool::s_shared(40);
+
 #endif
 
 }
 
-#if (defined(ANDROID) || defined(__ANDROID__))
-extern "C" jint JNI_OnLoad(JavaVM* vm, void* reserved)
-{
-   JNIEnv* env;
-   if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK)
-   {
-      return -1;
-   }
-
-   crossplat::JVM = vm;
-   return JNI_VERSION_1_6;
+#if defined(__ANDROID__)
+void cpprest_init(JavaVM* vm) {
+    crossplat::JVM = vm;
 }
 #endif
+