Merge pull request emscripten-core#1 from rstz/pthreadfs-initial

Add PThreadFS folder

.gitignore

@@ -23,3 +23,9 @@ htmlcov/
 coverage.xml
 
 .DS_Store
+
+# PThreadfs
+pthreadfs/examples/cache
+pthreadfs/examples/dist
+pthreadfs/examples/out
+pthreadfs/examples/sqlite-src

pthreadfs/README.md

@@ -0,0 +1,157 @@
+# PThreadFS
+
+The Emscripten Pthread File System (PThreadFS) unlocks using (partly) asynchronous storage APIs such as [OPFS Access Handles](https://docs.google.com/document/d/121OZpRk7bKSF7qU3kQLqAEUVSNxqREnE98malHYwWec/edit#heading=h.gj2fudnvy982) through the Emscripten File System API. This enables C++ applications compiled through Emscripten to use persistent storage without using [Asyncify](https://emscripten.org/docs/porting/asyncify.html). PThreadFS requires only minimal modifications to the C++ code and nearly achieves feature parity with the Emscripten's classic File System API.
+
+PThreadFS works by replacing Emscripten's file system API with a new API that proxies all file system operations to a dedicated pthread. This dedicated thread maintains a virtual file system that can use different APIs as backend (very similar to the way Emscripten's VFS is designed). In particular, PThreadFS comes with built-in support for asynchronous backends such as [OPFS Access Handles](https://docs.google.com/document/d/121OZpRk7bKSF7qU3kQLqAEUVSNxqREnE98malHYwWec/edit#heading=h.gj2fudnvy982).
+Although the underlying storage API is asynchronous, PThreadFS makes it appear synchronous to the C++ application.
+
+The code is still prototype quality and **should not be used in a production environment** for the time being.
+
+## Enable and detect OPFS in Chrome
+
+OPFS Access Handles require very recent versions of Google Chrome Canary. PThreadFS has been successfully tested with Version 94.0.4597.0.
+
+To enable the API, the " --enable-features=FileSystemAccessAccessHandle" flag must be set when starting Chrome from the console. On MacOS, this can be done through
+```
+open -a /Applications/Google\ Chrome\ Canary.app --args --enable-features=FileSystemAccessAccessHandle
+```
+
+Support for AccesHandles in OPFS can be detected through
+```
+async function detectAccessHandleWorker() {
+  const root = await navigator.storage.getDirectory();
+  const file = await root.getFileHandle('access-handle-detect', { create: true });
+  const present = file.createSyncAccessHandle != undefined;
+  await root.removeEntry('access-handle-detect');
+  return present;
+}
+
+async function detectAccessHandleMainThread() {
+  const detectAccessHandleAndPostMessage = async function(){
+    const root = await navigator.storage.getDirectory();
+    const file = await root.getFileHandle('access-handle-detect', { create: true });
+    const present = file.createSyncAccessHandle != undefined;
+    await root.removeEntry('access-handle-detect');
+    postMessage(present);
+  };
+
+  return new Promise((resolve, reject) => {
+    const detectBlob = new Blob(['('+detectAccessHandleAndPostMessage.toString()+')()'], {type: 'text/javascript'})
+    const detectWorker = new Worker(window.URL.createObjectURL(detectBlob));
+    
+    detectWorker.onmessage = result => {
+      resolve(result.data);
+      detectWorker.terminate();
+    };
+
+    detectWorker.onerror = error => {
+      reject(error);
+      detectWorker.terminate();
+    };
+  });
+}
+```
+
+## Getting the code
+
+PthreadFS is available on Github in the [emscripten-pthreadfs](https://github.com/rstz/emscripten-pthreadfs) repository. All code resides in the `pthreadfs` folder. It should be usable with any up-to-date Emscripten version. 
+
+There is **no need** to use a fork of Emscripten itself since all code operates in user-space.
+
+## Using PThreadFS in a project
+
+In order to use the code in a new project, you only need the three files in the `pthreadfs` folder: `pthreadfs_library.js`, `pthreadfs.cpp` and `pthreadfs.h`. The files are included as follows:
+
+### Code changes
+
+- Include `pthreadfs.h` in the C++ file containing `main()`:
+```
+#include "pthreadfs.h"
+```
+- Call `emscripten_init_pthreadfs();` at the top of `main()` (or before any file system syscalls).
+- PThreadFS maintains a virtual file system. The OPFS backend is mounted at `/filesystemaccess/`. Only files in this folder are persisted between sessions. All other files will be stored in-memory through MEMFS.
+
+### Build process changes
+
+There are two changes required to build a project with PThreadFS:
+- Compile `pthreadfs.h` and `pthreadfs.cpp` and link the resulting object to your application. Add `-pthread` to the compiler flag to include support for pthreads.
+- Add the following options to the linking step:
+```
+-pthread -O3 -s PROXY_TO_PTHREAD --js-library=library_pthreadsfs.js
+```
+**Example**
+If your build process was 
+```shell
+emcc myproject.cpp -o myproject.html
+```
+Your new build step should be
+```shell
+emcc -pthread -s PROXY_TO_PTHREAD -O3 --js-library=library_pthreadfs.js myproject.cpp pthreadfs.cpp -o myproject.html
+```
+
+### Advanced Usage
+
+If you want to modify the PThreadFS file system directly, you may use the macro `EM_PTHREADFS_ASM()` defined in `pthreadfs.h`. The macro allows you to run asynchrononous Javascript on the Pthread hosting the PThreadFS file system. For example, you may create a folder in the virtual file system by calling
+```
+EM_PTHREADFS_ASM(
+  await PThreadFS.mkdir('mydirectory');
+);
+```
+See `pthreadfs/examples/emscripten-tests/` for exemplary usage.
+
+
+## Known Limitations
+
+- The code is still prototype quality and **should not be used in a production environment** yet. It is possible that the use of PThreadFS might lead to subtle bugs in other libraries.
+- PThreadFS requires PROXY_TO_PTHREAD to be active. In particular, no system calls interacting with the file system should be called from the main thread.
+- Some functionality of the Emscripten File System API is missing, such as sockets, IndexedDB integration and support for XHRequests.
+- PThreadFS depends on C++ libraries. `EM_PTRHEADFS_ASM()` cannot be used within C files (although initializing through `emscripten_init_pthreadfs()` is possible, see the `pthreadfs/examples/sqlite-speedtest` for an example).
+- Only in-memory storage (MEMFS) and OPFS Access Handles (FSAFS) are available as backends for PThreadFS. 
+
+  There is no support (yet) for persisting data into IndexedDB (the way IDBFS works). Limited support is available for the Storage Foundation API as backend.
+- Performance is good if and only if full optimizations (compiler option `-O3`) are enabled and DevTools are closed.
+- Using stdout from C++ only prints to the Javascript console, not the Emscripten-generated html file.
+
+
+## Examples
+
+The examples are provided to show how projects can be transformed to use PThreadFS. To build them, navigate to the `pthreadfs/examples/` folder and run `make all`. You need to have the [Emscripten SDK](https://emscripten.org/docs/getting_started/downloads.html) activated for the build process to succeed.
+
+### SQLite Speedtest
+
+This example shows how to compile and run the [speedtest1](https://www.sqlite.org/cpu.html) from the SQLite project in the browser.
+
+The Makefile downloads the source of the speedtest and sqlite3 directly from <https://sqlite.org>.
+
+To compile, navigate to the `pthreadfs/examples/` directory and run
+
+```shell
+make sqlite-speedtest
+cd dist/sqlite-speedtest
+python3 -m http.server 8888
+```
+Then open the following link in a Chrome instance with the
+_OPFS Access Handles_ [enabled](#enable-and-detect-opfs-in-chrome):
+
+[localhost:8888/sqlite-speedtest](http://localhost:8888/sqlite-speedtest). The results of the speedtest can be found in the DevTools console.
+
+### Other tests
+
+The folder `pthreadfs/examples/emscripten-tests` contains a number of other file system tests taken from Emscripten's standard test suite.
+
+To compile, navigate to the `pthreadfs/examples/` directory and run
+
+```shell
+make emscripten-tests
+cd dist/emscripten-tests
+python3 -m http.server 8888
+```
+Then open the following link in a Chrome instance with the
+_OPFS Access Handles_ [enabled](#enable-and-detect-opfs-in-chrome):
+
+[localhost:8888/emscripten-tests](http://localhost:8888/emscripten-tests) and choose a test. The results of the test can be found in the DevTools console.
+
+## Authors
+- Richard Stotz (<[email protected]>)
+
+This is not an official Google product.

pthreadfs/examples/Makefile

@@ -0,0 +1,127 @@
+# Emscripten
+EMCC = emcc
+
+# Define some folders
+EMTESTS = emscripten-tests
+SQLITETESTS = sqlite-speedtest
+OBJ = out/bc
+
+PTHREADFS_JS = ../library_pthreadfs.js
+PTHREADFS_H = ../pthreadfs.h
+PTHREADFS_CPP = ../pthreadfs.cpp
+
+# I got this handy makefile syntax from : https://github.com/mandel59/sqlite-wasm (MIT License) Credited in LICENSE
+# To use another version of Sqlite, visit https://www.sqlite.org/download.html and copy the appropriate values here:
+SQLITE_AMALGAMATION = sqlite-amalgamation-3350000
+SQLITE_AMALGAMATION_ZIP_URL = https://www.sqlite.org/2021/sqlite-amalgamation-3350000.zip
+SQLITE_AMALGAMATION_ZIP_SHA1 = ba64bad885c9f51df765a9624700747e7bf21b79
+SQLITE_H = sqlite3.h
+SQLITE_SPEEDTEST = speedtest1.c
+SQLITE_SPEEDTEST_URL = https://sqlite.org/src/raw/5e5b805f24cc939656058f6a498f5a2160f9142e4815c54faf758ec798d4cdad?at=speedtest1.c
+SQLITE_SPEEDTEST_SHA1 = f0edde2ad68f090e4676ac30042e0f6b765a8528
+
+## cache
+cache/$(SQLITE_AMALGAMATION).zip:
+	mkdir -p cache
+	curl -LsSf '$(SQLITE_AMALGAMATION_ZIP_URL)' -o $@
+
+cache/$(SQLITE_SPEEDTEST):
+	mkdir -p cache
+	curl -LsSf '$(SQLITE_SPEEDTEST_URL)' -o $@
+
+
+## sqlite-src
+.PHONY: sqlite-src
+sqlite-src: sqlite-src/$(SQLITE_AMALGAMATION) sqlite-src/$(SQLITE_SPEEDTEST)
+
+sqlite-src/$(SQLITE_AMALGAMATION): cache/$(SQLITE_AMALGAMATION).zip sqlite-src/$(SQLITE_AMALGAMATION)/$(EXTENSION_FUNCTIONS)
+	mkdir -p sqlite-src/$(SQLITE_AMALGAMATION)
+	echo '$(SQLITE_AMALGAMATION_ZIP_SHA1)  ./cache/$(SQLITE_AMALGAMATION).zip' > cache/check.txt
+	shasum -c cache/check.txt
+	# We don't delete the sqlite_amalgamation folder. That's a job for clean
+	# Also, the extension functions get copied here, and if we get the order of these steps wrong,
+	# this step could remove the extension functions, and that's not what we want
+	unzip -u 'cache/$(SQLITE_AMALGAMATION).zip' -d sqlite-src/
+	touch $@
+
+sqlite-src/$(SQLITE_AMALGAMATION)/$(SQLITE_H): sqlite-src/$(SQLITE_AMALGAMATION)
+
+sqlite-src/$(SQLITE_SPEEDTEST): cache/$(SQLITE_SPEEDTEST)
+	mkdir -p sqlite-src/$(SQLITE_AMALGAMATION)
+	echo '$(SQLITE_SPEEDTEST_SHA1)  ./cache/$(SQLITE_SPEEDTEST)' > cache/check.txt
+	shasum -c cache/check.txt
+	cp 'cache/$(SQLITE_SPEEDTEST)' $@
+	echo 'extern void emscripten_init_pthreadfs();' > includeline.tmp
+	mv $@ input.tmp
+	cat includeline.tmp input.tmp > $@
+	rm input.tmp includeline.tmp
+	sed -i '' -e '/int main(/a\'$$'\n''emscripten_init_pthreadfs();' $@
+
+
+# build options
+OPTIMIZATION_LEVEL = O3
+
+CFLAGS = \
+	-$(OPTIMIZATION_LEVEL) \
+	-Wall \
+	-pthread \
+	-I..
+
+CFLAGS_SQLITE = \
+	$(CFLAGS) \
+	-DSQLITE_ENABLE_MEMSYS5 \
+	-D_HAVE_SQLITE_CONFIG_H \
+	-DSQLITE_OMIT_LOAD_EXTENSION \
+	-DSQLITE_DISABLE_LFS \
+	-DSQLITE_THREADSAFE=0 \
+	-DSQLITE_ENABLE_NORMALIZE \
+	-Isqlite-src/$(SQLITE_AMALGAMATION)/
+
+LINK_FLAGS =  \
+	-pthread \
+	-s PROXY_TO_PTHREAD \
+	-s INITIAL_MEMORY=134217728
+
+.PHONY: all 
+all: sqlite-speedtest emscripten-tests
+
+.PHONY: clean
+clean:
+	rm -rf dist/*
+	rm -rf out/
+	rm -f cache/*
+	rm -rf sqlite-src/
+
+$(OBJ)/sqlite3.o: sqlite-src/$(SQLITE_AMALGAMATION)
+	mkdir -p $(OBJ)
+	$(EMCC) $(CFLAGS) -c sqlite-src/$(SQLITE_AMALGAMATION)/sqlite3.c -o $@
+
+$(OBJ)/speedtest1.o: sqlite-src/$(SQLITE_SPEEDTEST) sqlite-src/$(SQLITE_AMALGAMATION)
+	mkdir -p $(OBJ)
+	$(EMCC) $(CFLAGS) -Isqlite-src/$(SQLITE_AMALGAMATION)/ -c $< -o $@
+
+$(OBJ)/pthreadfs.o : $(PTHREADFS_CPP)
+	mkdir -p $(OBJ)
+	$(EMCC) -c $(CFLAGS) $< -o $@
+
+$(OBJ)/%.o : $(EMTESTS)/%.cpp
+	mkdir -p $(OBJ)
+	$(EMCC) -c $(CFLAGS) $< -o $@
+
+# Don't delete my precious object files
+.PRECIOUS: $(OBJ)/%.out
+
+.PHONY: sqlite-speedtest
+sqlite-speedtest: dist/sqlite-speedtest/index.html
+dist/sqlite-speedtest/index.html: $(OBJ)/speedtest1.o $(OBJ)/sqlite3.o $(OBJ)/pthreadfs.o $(PTHREADFS_JS) $(SQLITETESTS)/sqlite-speedtest-prejs.js
+	mkdir -p dist/sqlite-speedtest
+	$(EMCC) $(LINK_FLAGS) --pre-js=$(SQLITETESTS)/sqlite-speedtest-prejs.js --js-library=$(PTHREADFS_JS) $< $(word 2,$^) $(word 3,$^) -o $@ 
+
+.PHONY: emscripten-tests
+emscripten-tests: $(addprefix dist/, $(addsuffix .html, $(basename $(wildcard $(EMTESTS)/*.cpp))))
+	@echo 'building emscripten-tests' $?
+
+dist/$(EMTESTS)/%.html : $(OBJ)/%.o $(OBJ)/pthreadfs.o $(PTHREADFS_JS)
+	mkdir -p dist/$(EMTESTS)
+	$(EMCC) $(LINK_FLAGS) --js-library=$(PTHREADFS_JS) $< $(word 2,$^) -o $@
+

pthreadfs/examples/emscripten-tests/access.cpp

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2011 The Emscripten Authors.  All rights reserved.
+ * Emscripten is available under two separate licenses, the MIT license and the
+ * University of Illinois/NCSA Open Source License.  Both these licenses can be
+ * found in the LICENSE file.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <emscripten.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include "pthreadfs.h"
+
+int main() {
+  emscripten_init_pthreadfs();
+  EM_PTHREADFS_ASM(
+    await PThreadFS.mkdir('working');
+    await PThreadFS.chdir('working');
+    await PThreadFS.writeFile('forbidden', ""); await PThreadFS.chmod('forbidden', 0o000);
+    await PThreadFS.writeFile('readable',  ""); await PThreadFS.chmod('readable',  0o444);
+    await PThreadFS.writeFile('writeable', ""); await PThreadFS.chmod('writeable', 0o222);
+    await PThreadFS.writeFile('allaccess', ""); await PThreadFS.chmod('allaccess', 0o777);
+  );
+  // Empty path checks #9136 fix
+  char* files[] = {"readable", "writeable",
+                   "allaccess", "forbidden", "nonexistent", ""};
+  for (int i = 0; i < sizeof files / sizeof files[0]; i++) {
+    printf("F_OK(%s): %d\n", files[i], access(files[i], F_OK));
+    printf("errno: %d\n", errno);
+    errno = 0;
+    printf("R_OK(%s): %d\n", files[i], access(files[i], R_OK));
+    printf("errno: %d\n", errno);
+    errno = 0;
+    printf("X_OK(%s): %d\n", files[i], access(files[i], X_OK));
+    printf("errno: %d\n", errno);
+    errno = 0;
+    printf("W_OK(%s): %d\n", files[i], access(files[i], W_OK));
+    printf("errno: %d\n", errno);
+    errno = 0;
+    printf("\n");
+  }
+
+  EM_PTHREADFS_ASM(
+    await PThreadFS.writeFile('filetorename',  'renametest');
+  );
+
+  rename("filetorename", "renamedfile");
+
+  errno = 0;
+  printf("F_OK(%s): %d\n", "filetorename", access("filetorename", F_OK));
+  printf("errno: %d\n", errno);
+  errno = 0;
+  printf("F_OK(%s): %d\n", "renamedfile", access("renamedfile", F_OK));
+  printf("errno: %d\n", errno);
+  return 0;
+}