Split the libdawn target in components with a single purpose.

The functionality of the dawn_headers and libdawn targets are split into
the following targets:

 - dawn_headers: the new version only exposes the "dawn.h" C API and no
   longer includes the C++ API.
 - dawncpp: the header and implementation of the C++ API that wraps the
   C API. This is unbundled from the rest so the C++ API can be used
   with libdawn_proc or other libraries implementing the C API.
 - libdawn_proc: A DawnProcTable-backend implementation of the C API.

This is needed because in follow-up commit there will be three libraries
implementing the C API: libdawn_proc that trampolines where we want, and
libdawn_native/wire that don't have trampolines for better perf.

BUG=dawn:22

Change-Id: I5d941f0d98e5a4b633e14d67eb5269f7924f0647
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/12160
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

BUILD.gn

@@ -749,7 +749,8 @@ test("dawn_unittests") {
     ":libdawn_wire",
     ":mock_dawn_gen",
     "${dawn_root}/src/common",
-    "${dawn_root}/src/dawn:libdawn",
+    "${dawn_root}/src/dawn:dawncpp",
+    "${dawn_root}/src/dawn:libdawn_proc",
     "third_party:gmock_and_gtest",
   ]
 
@@ -840,7 +841,8 @@ source_set("dawn_end2end_tests_sources") {
     ":libdawn_native",
     ":libdawn_wire",
     "${dawn_root}/src/common",
-    "${dawn_root}/src/dawn:libdawn",
+    "${dawn_root}/src/dawn:dawncpp",
+    "${dawn_root}/src/dawn:libdawn_proc",
     "third_party:gmock_and_gtest",
   ]
 
@@ -917,7 +919,8 @@ source_set("dawn_white_box_tests_sources") {
     ":libdawn_native_sources",
     ":libdawn_wire",
     "${dawn_root}/src/common",
-    "${dawn_root}/src/dawn:libdawn",
+    "${dawn_root}/src/dawn:dawncpp",
+    "${dawn_root}/src/dawn:libdawn_proc",
     "third_party:gmock_and_gtest",
   ]
 
@@ -950,7 +953,8 @@ test("dawn_end2end_tests") {
     ":libdawn_native",
     ":libdawn_wire",
     "${dawn_root}/src/common",
-    "${dawn_root}/src/dawn:libdawn",
+    "${dawn_root}/src/dawn:dawncpp",
+    "${dawn_root}/src/dawn:libdawn_proc",
     "third_party:gmock_and_gtest",
   ]
 
@@ -982,7 +986,8 @@ test("dawn_perf_tests") {
     ":libdawn_native",
     ":libdawn_wire",
     "${dawn_root}/src/common",
-    "${dawn_root}/src/dawn:libdawn",
+    "${dawn_root}/src/dawn:dawncpp",
+    "${dawn_root}/src/dawn:libdawn_proc",
     "third_party:gmock_and_gtest",
   ]
 
@@ -1059,7 +1064,8 @@ if (dawn_standalone) {
       ":libdawn_native",
       ":libdawn_wire",
       "${dawn_root}/src/common",
-      "${dawn_root}/src/dawn:libdawn",
+      "${dawn_root}/src/dawn:dawncpp",
+      "${dawn_root}/src/dawn:libdawn_proc",
     ]
     public_configs = [ "${dawn_root}/src/common:dawn_internal" ]
   }

README.md

@@ -5,12 +5,16 @@ It exposes a C/C++ API that maps almost one-to-one to the WebGPU IDL and can be
 
 Dawn provides several WebGPU building blocks:
  - **WebGPU C/C++ headers** that applications and other building blocks use.
+   - The main C header for the WebGPU API.
+   - Definition of a structure of all function pointers for this specific Dawn version (called "proctable").
+   - A C++ wrapper for the C header.
  - **A "native" implementation of WebGPU** using platforms' GPU APIs:
    - **D3D12** on Windows 10
    - **Metal** on OSX (and eventually iOS)
-   - **Vulkan** on Windows, Linux (eventually ChromeOS and Android too)
+   - **Vulkan** on Windows, Linux (eventually ChromeOS, Android and Fuchsia too)
    - OpenGL as best effort where available
  - **A client-server implementation of WebGPU** for applications that are in a sandbox without access to native drivers
+ - **A Dawn proc-table backend implementation of WebGPU** for applications what want to be able to switch at runtime between native or client-server mode.
 
 ## Directory structure
 

examples/SampleUtils.cpp

@@ -20,6 +20,7 @@
 #include "utils/TerribleCommandBuffer.h"
 
 #include <dawn/dawn.h>
+#include <dawn/dawn_proc.h>
 #include <dawn/dawn_wsi.h>
 #include <dawn/dawncpp.h>
 #include <dawn_native/DawnNative.h>
@@ -160,7 +161,7 @@ dawn::Device CreateCppDawnDevice() {
             break;
     }
 
-    dawnSetProcs(&procs);
+    dawnProcSetProcs(&procs);
     procs.deviceSetUncapturedErrorCallback(cDevice, PrintDeviceError, nullptr);
     return dawn::Device::Acquire(cDevice);
 }

generator/dawn_json_generator.py

@@ -453,7 +453,7 @@ class MultiGeneratorFromDawnJSON(Generator):
         return 'Generates code for various target from Dawn.json.'
 
     def add_commandline_arguments(self, parser):
-        allowed_targets = ['dawn_headers', 'libdawn', 'mock_dawn', 'dawn_wire', "dawn_native_utils"]
+        allowed_targets = ['dawn_headers', 'dawncpp', 'dawn_proc', 'mock_dawn', 'dawn_wire', "dawn_native_utils"]
 
         parser.add_argument('--dawn-json', required=True, type=str, help ='The DAWN JSON definition to use.')
         parser.add_argument('--wire-json', default=None, type=str, help='The DAWN WIRE JSON definition to use.')
@@ -495,11 +495,13 @@ class MultiGeneratorFromDawnJSON(Generator):
 
         if 'dawn_headers' in targets:
             renders.append(FileRender('api.h', 'src/include/dawn/dawn.h', [base_params, api_params, c_params]))
-            renders.append(FileRender('apicpp.h', 'src/include/dawn/dawncpp.h', [base_params, api_params, cpp_params]))
+            renders.append(FileRender('api_proc_table.h', 'src/include/dawn/dawn_proc_table.h', [base_params, api_params, c_params]))
 
-        if 'libdawn' in targets:
-            additional_params = {'native_methods': lambda typ: cpp_native_methods(api_params['types'], typ)}
-            renders.append(FileRender('api.c', 'src/dawn/dawn.c', [base_params, api_params, c_params]))
+        if 'dawn_proc' in targets:
+            renders.append(FileRender('api_proc.c', 'src/dawn/dawn_proc.c', [base_params, api_params, c_params]))
+
+        if 'dawncpp' in targets:
+            renders.append(FileRender('apicpp.h', 'src/include/dawn/dawncpp.h', [base_params, api_params, cpp_params]))
             renders.append(FileRender('apicpp.cpp', 'src/dawn/dawncpp.cpp', [base_params, api_params, cpp_params]))
 
         if 'mock_dawn' in targets:

generator/templates/api.h

@@ -84,23 +84,8 @@ typedef void (*DawnFenceOnCompletionCallback)(DawnFenceCompletionStatus status,
 {% endfor %}
 #endif  // !defined(DAWN_SKIP_PROCS)
 
-struct DawnProcTable_s {
-    {% for type in by_category["object"] %}
-        {% for method in native_methods(type) %}
-            {{as_cProc(type.name, method.name)}} {{as_varName(type.name, method.name)}};
-        {% endfor %}
-
-    {% endfor %}
-};
-typedef struct DawnProcTable_s DawnProcTable;
-
-// Stuff below is for convenience and will forward calls to a static DawnProcTable.
-
 #if !defined(DAWN_SKIP_DECLARATIONS)
 
-// Set which DawnProcTable will be used
-DAWN_EXPORT void dawnSetProcs(const DawnProcTable* procs);
-
 {% for type in by_category["object"] %}
     // Methods of {{type.name.CamelCase()}}
     {% for method in native_methods(type) %}

generator/templates/api_proc.c

@@ -12,13 +12,13 @@
 //* See the License for the specific language governing permissions and
 //* limitations under the License.
 
-#include "dawn/dawn.h"
+#include "dawn/dawn_proc.h"
 
 static DawnProcTable procs;
 
 static DawnProcTable nullProcs;
 
-void dawnSetProcs(const DawnProcTable* procs_) {
+void dawnProcSetProcs(const DawnProcTable* procs_) {
     if (procs_) {
         procs = *procs_;
     } else {

generator/templates/api_proc_table.h

@@ -0,0 +1,29 @@
+//* Copyright 2019 The Dawn Authors
+//*
+//* Licensed under the Apache License, Version 2.0 (the "License");
+//* you may not use this file except in compliance with the License.
+//* You may obtain a copy of the License at
+//*
+//*     http://www.apache.org/licenses/LICENSE-2.0
+//*
+//* Unless required by applicable law or agreed to in writing, software
+//* distributed under the License is distributed on an "AS IS" BASIS,
+//* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//* See the License for the specific language governing permissions and
+//* limitations under the License.
+
+#ifndef DAWN_DAWN_PROC_TABLE_H_
+#define DAWN_DAWN_PROC_TABLE_H_
+
+#include "dawn/dawn.h"
+
+typedef struct DawnProcTable {
+    {% for type in by_category["object"] %}
+        {% for method in native_methods(type) %}
+            {{as_cProc(type.name, method.name)}} {{as_varName(type.name, method.name)}};
+        {% endfor %}
+
+    {% endfor %}
+} DawnProcTable;
+
+#endif  // DAWN_DAWN_PROC_TABLE_H_

generator/templates/apicpp.h

@@ -16,7 +16,6 @@
 #define DAWN_DAWNCPP_H_
 
 #include "dawn/dawn.h"
-#include "dawn/dawn_export.h"
 #include "dawn/EnumClassBitmasks.h"
 
 namespace dawn {
@@ -143,7 +142,7 @@ namespace dawn {
 
 {% macro render_cpp_method_declaration(type, method) %}
     {% set CppType = as_cppType(type.name) %}
-    DAWN_EXPORT {{as_cppType(method.return_type.name)}} {{method.name.CamelCase()}}(
+    {{as_cppType(method.return_type.name)}} {{method.name.CamelCase()}}(
         {%- for arg in method.arguments -%}
             {%- if not loop.first %}, {% endif -%}
             {%- if arg.type.category == "object" and arg.annotation == "value" -%}
@@ -170,8 +169,8 @@ namespace dawn {
 
           private:
             friend ObjectBase<{{CppType}}, {{CType}}>;
-            static DAWN_EXPORT void DawnReference({{CType}} handle);
-            static DAWN_EXPORT void DawnRelease({{CType}} handle);
+            static void DawnReference({{CType}} handle);
+            static void DawnRelease({{CType}} handle);
         };
 
     {% endfor %}

generator/templates/dawn_wire/server/ServerBase.h

@@ -15,6 +15,7 @@
 #ifndef DAWNWIRE_SERVER_SERVERBASE_H_
 #define DAWNWIRE_SERVER_SERVERBASE_H_
 
+#include "dawn/dawn_proc_table.h"
 #include "dawn_wire/Wire.h"
 #include "dawn_wire/WireCmd_autogen.h"
 #include "dawn_wire/WireDeserializeAllocator.h"

generator/templates/mock_api.h

@@ -15,8 +15,9 @@
 #ifndef MOCK_DAWN_H
 #define MOCK_DAWN_H
 
-#include <gmock/gmock.h>
 #include <dawn/dawn.h>
+#include <dawn/dawn_proc_table.h>
+#include <gmock/gmock.h>
 
 #include <memory>
 

src/dawn/BUILD.gn

@@ -17,6 +17,14 @@ import("../../scripts/dawn_overrides_with_defaults.gni")
 import("${dawn_root}/generator/dawn_generator.gni")
 import("${dawn_root}/scripts/dawn_component.gni")
 
+# Temporary group to not break Chromium `gn check` on Dawn CQ.
+group("libdawn") {
+  deps = [
+    ":dawncpp",
+    ":libdawn_proc",
+  ]
+}
+
 ###############################################################################
 # Dawn headers
 ###############################################################################
@@ -24,46 +32,65 @@ import("${dawn_root}/scripts/dawn_component.gni")
 dawn_json_generator("dawn_headers_gen") {
   target = "dawn_headers"
   outputs = [
-    "src/include/dawn/dawncpp.h",
     "src/include/dawn/dawn.h",
+    "src/include/dawn/dawn_proc_table.h",
   ]
 }
 
 source_set("dawn_headers") {
   all_dependent_configs = [ "${dawn_root}/src/common:dawn_public_include_dirs" ]
-  deps = [
+  public_deps = [
     ":dawn_headers_gen",
   ]
 
   sources = get_target_outputs(":dawn_headers_gen")
   sources += [
-    "${dawn_root}/src/include/dawn/EnumClassBitmasks.h",
     "${dawn_root}/src/include/dawn/dawn_export.h",
     "${dawn_root}/src/include/dawn/dawn_wsi.h",
   ]
 }
 
 ###############################################################################
-# libdawn
+# Dawn C++ wrapper
 ###############################################################################
 
-dawn_json_generator("libdawn_gen") {
-  target = "libdawn"
+dawn_json_generator("dawncpp_gen") {
+  target = "dawncpp"
   outputs = [
     "src/dawn/dawncpp.cpp",
-    "src/dawn/dawn.c",
+    "src/include/dawn/dawncpp.h",
   ]
 }
 
-dawn_component("libdawn") {
+source_set("dawncpp") {
+  deps = [
+    ":dawn_headers",
+    ":dawncpp_gen",
+  ]
+  sources = get_target_outputs(":dawncpp_gen")
+  sources += [ "${dawn_root}/src/include/dawn/EnumClassBitmasks.h" ]
+}
+
+###############################################################################
+# libdawn_proc
+###############################################################################
+
+dawn_json_generator("libdawn_proc_gen") {
+  target = "dawn_proc"
+  outputs = [
+    "src/dawn/dawn_proc.c",
+  ]
+}
+
+dawn_component("libdawn_proc") {
   DEFINE_PREFIX = "DAWN"
 
   public_deps = [
     ":dawn_headers",
   ]
-
   deps = [
-    ":libdawn_gen",
+    ":libdawn_proc_gen",
   ]
-  sources = get_target_outputs(":libdawn_gen")
+  sources = get_target_outputs(":libdawn_proc_gen")
+  sources += [ "${dawn_root}/src/include/dawn/dawn_proc.h" ]
 }

src/fuzzers/BUILD.gn

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import("../../scripts/dawn_overrides_with_defaults.gni")
 import("//build_overrides/build.gni")
+import("../../scripts/dawn_overrides_with_defaults.gni")
 
 # We only have libfuzzer in Chromium builds but if we build fuzzer targets only
 # there, we would risk breaking fuzzer targets all the time when making changes
@@ -127,7 +127,8 @@ dawn_fuzzer_test("dawn_wire_server_and_frontend_fuzzer") {
     "${dawn_root}/:libdawn_native_static",
     "${dawn_root}/:libdawn_wire_static",
     "${dawn_root}/src/common",
-    "${dawn_root}/src/dawn:libdawn_static",
+    "${dawn_root}/src/dawn:dawncpp",
+    "${dawn_root}/src/dawn:libdawn_proc",
   ]
 
   additional_configs = [ "${dawn_root}/src/common:dawn_internal" ]

src/fuzzers/DawnWireServerAndFrontendFuzzer.cpp

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include "common/Assert.h"
+#include "dawn/dawn_proc.h"
 #include "dawn/dawncpp.h"
 #include "dawn_native/DawnNative.h"
 #include "dawn_wire/WireServer.h"
@@ -56,7 +57,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
     originalDeviceCreateSwapChain = procs.deviceCreateSwapChain;
     procs.deviceCreateSwapChain = ErrorDeviceCreateSwapChain;
 
-    dawnSetProcs(&procs);
+    dawnProcSetProcs(&procs);
 
     // Create an instance and find the null adapter to create a device with.
     std::unique_ptr<dawn_native::Instance> instance = std::make_unique<dawn_native::Instance>();

src/include/dawn/dawn_proc.h

@@ -0,0 +1,36 @@
+// Copyright 2019 The Dawn Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef DAWN_DAWN_PROC_H_
+#define DAWN_DAWN_PROC_H_
+
+#include "dawn/dawn.h"
+#include "dawn/dawn_proc_table.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Sets the static proctable used by libdawn_proc to implement the Dawn entrypoints. Passing NULL
+// for `procs` sets up the null proctable that contains only null function pointers. It is the
+// default value of the proctable. Setting the proctable back to null is good practice when you
+// are done using libdawn_proc since further usage will cause a segfault instead of calling an
+// unexpected function.
+DAWN_EXPORT void dawnProcSetProcs(const DawnProcTable* procs);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // DAWN_DAWN_PROC_H_

src/include/dawn_native/DawnNative.h

@@ -16,6 +16,7 @@
 #define DAWNNATIVE_DAWNNATIVE_H_
 
 #include <dawn/dawn.h>
+#include <dawn/dawn_proc_table.h>
 #include <dawn_native/dawn_native_export.h>
 
 #include <string>

src/include/dawn_wire/WireClient.h

@@ -15,10 +15,11 @@
 #ifndef DAWNWIRE_WIRECLIENT_H_
 #define DAWNWIRE_WIRECLIENT_H_
 
-#include <memory>
-
+#include "dawn/dawn_proc_table.h"
 #include "dawn_wire/Wire.h"
 
+#include <memory>
+
 namespace dawn_wire {
 
     namespace client {

src/include/dawn_wire/WireServer.h

@@ -19,6 +19,8 @@
 
 #include "dawn_wire/Wire.h"
 
+struct DawnProcTable;
+
 namespace dawn_wire {
 
     namespace server {

src/tests/DawnTest.cpp

@@ -18,6 +18,7 @@
 #include "common/Constants.h"
 #include "common/Math.h"
 #include "common/Platform.h"
+#include "dawn/dawn_proc.h"
 #include "dawn_native/DawnNative.h"
 #include "dawn_wire/WireClient.h"
 #include "dawn_wire/WireServer.h"
@@ -262,7 +263,7 @@ DawnTestBase::~DawnTestBase() {
         backendProcs.deviceRelease(backendDevice);
     }
 
-    dawnSetProcs(nullptr);
+    dawnProcSetProcs(nullptr);
 }
 
 bool DawnTestBase::IsD3D12() const {
@@ -452,7 +453,7 @@ void DawnTestBase::SetUp() {
 
     // Set up the device and queue because all tests need them, and DawnTestBase needs them too for
     // the deferred expectations.
-    dawnSetProcs(&procs);
+    dawnProcSetProcs(&procs);
     device = dawn::Device::Acquire(cDevice);
     queue = device.CreateQueue();
 

src/tests/DawnTest.h

@@ -15,6 +15,7 @@
 #ifndef TESTS_DAWNTEST_H_
 #define TESTS_DAWNTEST_H_
 
+#include "dawn/dawn_proc_table.h"
 #include "dawn/dawncpp.h"
 #include "dawn_native/DawnNative.h"
 

src/tests/unittests/validation/ValidationTest.cpp

@@ -16,6 +16,7 @@
 
 #include "common/Assert.h"
 #include "dawn/dawn.h"
+#include "dawn/dawn_proc.h"
 #include "dawn_native/NullBackend.h"
 
 ValidationTest::ValidationTest() {
@@ -37,7 +38,7 @@ ValidationTest::ValidationTest() {
     ASSERT(foundNullAdapter);
 
     DawnProcTable procs = dawn_native::GetProcs();
-    dawnSetProcs(&procs);
+    dawnProcSetProcs(&procs);
 
     device = CreateDeviceFromAdapter(adapter, std::vector<const char*>());
 }
@@ -64,7 +65,7 @@ ValidationTest::~ValidationTest() {
     // We need to destroy Dawn objects before setting the procs to null otherwise the dawn*Release
     // will call a nullptr
     device = dawn::Device();
-    dawnSetProcs(nullptr);
+    dawnProcSetProcs(nullptr);
 }
 
 void ValidationTest::TearDown() {

src/tests/unittests/wire/WireTest.cpp

@@ -14,6 +14,7 @@
 
 #include "tests/unittests/wire/WireTest.h"
 
+#include "dawn/dawn_proc.h"
 #include "dawn_wire/WireClient.h"
 #include "dawn_wire/WireServer.h"
 #include "utils/TerribleCommandBuffer.h"
@@ -65,13 +66,13 @@ void WireTest::SetUp() {
 
     device = mWireClient->GetDevice();
     DawnProcTable clientProcs = mWireClient->GetProcs();
-    dawnSetProcs(&clientProcs);
+    dawnProcSetProcs(&clientProcs);
 
     apiDevice = mockDevice;
 }
 
 void WireTest::TearDown() {
-    dawnSetProcs(nullptr);
+    dawnProcSetProcs(nullptr);
 
     // Derived classes should call the base TearDown() first. The client must
     // be reset before any mocks are deleted.

src/utils/BackendBinding.h

@@ -15,7 +15,7 @@
 #ifndef UTILS_BACKENDBINDING_H_
 #define UTILS_BACKENDBINDING_H_
 
-#include "dawn/dawncpp.h"
+#include "dawn/dawn.h"
 #include "dawn_native/DawnNative.h"
 
 struct GLFWwindow;