Initial checkin of gRPC to third_party/

third_party/grpc/src/csharp/Grpc.Core/Internal/NativeExtension.cs

Index: third_party/grpc/src/csharp/Grpc.Core/Internal/NativeExtension.cs
diff --git a/third_party/grpc/src/csharp/Grpc.Core/Internal/NativeExtension.cs b/third_party/grpc/src/csharp/Grpc.Core/Internal/NativeExtension.cs
new file mode 100644
index 0000000000000000000000000000000000000000..282816d51e036b7a210aa0bb53bd99b3ce774998
--- /dev/null
+++ b/third_party/grpc/src/csharp/Grpc.Core/Internal/NativeExtension.cs
@@ -0,0 +1,177 @@
+#region Copyright notice and license
+
+// Copyright 2015-2016, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Globalization;
+using System.IO;
+using System.Reflection;
+
+using Grpc.Core.Logging;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// Takes care of loading C# native extension and provides access to PInvoke calls the library exports.
+    /// </summary>
+    internal sealed class NativeExtension
+    {
+        const string NativeLibrariesDir = "nativelibs";
+
+        static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<NativeExtension>();
+        static readonly object staticLock = new object();
+        static volatile NativeExtension instance;
+
+        readonly NativeMethods nativeMethods;
+
+        private NativeExtension()
+        {
+            this.nativeMethods = new NativeMethods(Load());
+            
+            // Redirect the the native logs as the very first thing after loading the native extension
+            // to make sure we don't lose any logs.
+            NativeLogRedirector.Redirect(this.nativeMethods);
+
+            DefaultSslRootsOverride.Override(this.nativeMethods);
+
+            Logger.Debug("gRPC native library loaded successfully.");
+        }
+
+        /// <summary>
+        /// Gets singleton instance of this class.
+        /// The native extension is loaded when called for the first time.
+        /// </summary>
+        public static NativeExtension Get()
+        {
+            if (instance == null)
+            {
+                lock (staticLock)
+                {
+                    if (instance == null) {
+                        instance = new NativeExtension();
+                    }
+                }
+            }
+            return instance;
+        }
+
+        /// <summary>
+        /// Provides access to the exported native methods.
+        /// </summary>
+        public NativeMethods NativeMethods
+        {
+            get { return this.nativeMethods; }
+        }
+
+        /// <summary>
+        /// Detects which configuration of native extension to load and load it.
+        /// </summary>
+        private static UnmanagedLibrary Load()
+        {
+            // TODO: allow customizing path to native extension (possibly through exposing a GrpcEnvironment property).
+
+            var libraryFlavor = string.Format("{0}_{1}", GetPlatformString(), GetArchitectureString());
+            var fullPath = Path.Combine(Path.GetDirectoryName(GetAssemblyPath()),
+                NativeLibrariesDir, libraryFlavor, GetNativeLibraryFilename());
+            return new UnmanagedLibrary(fullPath);
+        }
+
+        private static string GetAssemblyPath()
+        {
+            var assembly = typeof(NativeExtension).GetTypeInfo().Assembly;
+
+            // If assembly is shadowed (e.g. in a webapp), EscapedCodeBase is pointing
+            // to the original location of the assembly, and Location is pointing
+            // to the shadow copy. We care about the original location because
+            // the native dlls don't get shadowed.
+            var escapedCodeBase = assembly.EscapedCodeBase;
+            if (IsFileUri(escapedCodeBase))
+            {
+                return new Uri(escapedCodeBase).LocalPath;
+            }
+            return assembly.Location;
+        }
+
+        private static bool IsFileUri(string uri)
+        {
+            return uri.ToLowerInvariant().StartsWith(Uri.UriSchemeFile);
+        }
+
+        private static string GetPlatformString()
+        {
+            if (PlatformApis.IsWindows)
+            {
+                return "windows";
+            }
+            if (PlatformApis.IsLinux)
+            {
+                return "linux";
+            }
+            if (PlatformApis.IsMacOSX)
+            {
+                return "macosx";
+            }
+            throw new InvalidOperationException("Unsupported platform.");
+        }
+
+        // Currently, only Intel platform is supported.
+        private static string GetArchitectureString()
+        {
+            if (PlatformApis.Is64Bit)
+            {
+                return "x64";
+            }
+            else
+            {
+                return "x86";
+            }
+        }
+
+        // platform specific file name of the extension library
+        private static string GetNativeLibraryFilename()
+        {
+            if (PlatformApis.IsWindows)
+            {
+                return "grpc_csharp_ext.dll";
+            }
+            if (PlatformApis.IsLinux)
+            {
+                return "libgrpc_csharp_ext.so";
+            }
+            if (PlatformApis.IsMacOSX)
+            {
+                return "libgrpc_csharp_ext.dylib";
+            }
+            throw new InvalidOperationException("Unsupported platform.");
+        }
+    }
+}