Handle V8 heap snapshots well + allow custom snapshot generation

README.Linux.md

@@ -10,7 +10,23 @@ years ago, since Node.js requires such an old version.
 This means that you usually need to compile v8 on your own before
 you can start to compile & install v8js itself.
 
-Compile latest v8
+Snapshots
+---------
+
+V8 has (optional) support for so-called snapshots which speed up startup
+performance drastically.  Hence they are generally recommended for use.
+
+There are two flavours of snapshots: internal & external.
+
+Internal snapshots are built right into the V8 library (libv8.so file),
+so there's no need to handle them specially.
+
+Besides there are external snapshots (which are enabled unless configured
+otherwise).  If V8 is compiled with these, then V8Js needs to provide two
+"binary blobs" to V8, named `natives_blob.bin` and `snapshot_blob.bin`.
+In that case copy those two files to `/usr/share/v8/...`.
+
+Compile latest V8
 -----------------
 
 ```
@@ -25,11 +41,15 @@ fetch v8
 cd v8
 
 # (optional) If you'd like to build a certain version:
-git checkout 3.32.6
+git checkout 4.9.385.28
 gclient sync
 
-# Build (disable snapshots for V8 > 4.4.9.1)
-make native library=shared snapshot=off -j8
+# use libicu of operating system
+export GYP_DEFINES="use_system_icu=1"
+
+# Build (with internal snapshots)
+export GYPFLAGS="-Dv8_use_external_startup_data=0"
+make native library=shared snapshot=on -j8
 
 # Install to /usr
 sudo mkdir -p /usr/lib /usr/include
@@ -40,16 +60,9 @@ echo -e "create /usr/lib/libv8_libplatform.a\naddlib out/native/obj.target/tools
 
 Then add `extension=v8js.so` to your php.ini file. If you have a separate configuration for CLI, add it there also.
 
-* If the V8 library is newer than 4.4.9.1 you need to pass `snapshot=off` to
-  `make`, otherwise the V8 library will not be usable
-  (see V8 [Issue 4192](https://code.google.com/p/v8/issues/detail?id=4192))
 * If you don't want to overwrite the system copy of v8, replace `/usr` in
   the above commands with some other path like `/opt/v8` and then add
   `--with-v8js=/opt/v8` to the php-v8js `./configure` command below.
-* If you do that with a v8 library of 4.2 branch or newer, then you need
-  to fix the RUNPATH header in the v8js.so library so the libicui18n.so
-  is found. By default it is set to `$ORIGIN/lib.target/`, however the files
-  lie side by side. Use `chrpath -r '$ORIGIN' libv8.so` to fix.
 
 `libv8_libplatform.a` should not be copied directly since it's a thin
 archive, i.e. it contains only pointers to the build objects, which
@@ -62,7 +75,7 @@ Compile php-v8js itself
 
 ```
 cd /tmp
-git clone https://github.com/preillyme/v8js.git
+git clone https://github.com/phpv8/v8js.git
 cd v8js
 phpize
 ./configure

README.md

@@ -62,13 +62,15 @@ class V8Js
     /* Methods */
 
     /**
-     * Initializes and starts V8 engine and Returns new V8Js object with it's own V8 context.
+     * Initializes and starts V8 engine and returns new V8Js object with it's own V8 context.
+     * Snapshots are supported by V8 4.3.7 and higher.
      * @param string $object_name
      * @param array $variables
      * @param array $extensions
      * @param bool $report_uncaught_exceptions
+     * @param string $snapshot_blob
      */
-    public function __construct($object_name = "PHP", array $variables = NULL, array $extensions = NULL, $report_uncaught_exceptions = TRUE)
+    public function __construct($object_name = "PHP", array $variables = [], array $extensions = [], $report_uncaught_exceptions = TRUE, $snapshot_blob = NULL)
     {}
 
     /**
@@ -174,6 +176,16 @@ class V8Js
      */
     public static function getExtensions()
     {}
+
+    /**
+     * Creates a custom V8 heap snapshot with the provided JavaScript source embedded.
+     * Snapshots are supported by V8 4.3.7 and higher.  For older versions of V8 this
+     * extension doesn't provide this method.
+     * @param string $embed_source
+     * @return string|false
+     */
+    public static function createSnapshot($embed_source)
+    {}
 }
 
 final class V8JsScriptException extends Exception

config.m4

@@ -130,11 +130,6 @@ int main ()
     AC_MSG_ERROR([could not determine libv8 version])
   fi
 
-  AC_LANG_RESTORE
-  LIBS=$old_LIBS
-  LDFLAGS=$old_LDFLAGS
-  CPPFLAGS=$old_CPPFLAGS
-
   if test "$V8_API_VERSION" -ge 3029036 ; then
     dnl building for v8 3.29.36 or later, which requires us to
     dnl initialize and provide a platform; hence we need to
@@ -169,10 +164,101 @@ int main ()
         AC_MSG_ERROR([Please provide $static_link_extra_file next to the libv8.so, see README.md for details])
       fi
 
-      LDFLAGS="$LDFLAGS $static_link_dir/$static_link_extra_file"
+      LDFLAGS_libplatform="$static_link_dir/$static_link_extra_file"
     done
+
+    # modify flags for (possibly) succeeding V8 startup check
+    CPPFLAGS="$CPPFLAGS -I$V8_DIR"
+    LIBS="$LIBS $LDFLAGS_libplatform"
   fi
 
+  if test "$V8_API_VERSION" -ge 4004010 ; then
+    dnl building for v8 4.4.10 or later, which requires us to
+    dnl provide startup data, if V8 wasn't compiled with snapshot=off.
+    AC_MSG_CHECKING([whether V8 requires startup data])
+    AC_TRY_RUN([
+        #include <v8.h>
+        #include <libplatform/libplatform.h>
+        #include <stdlib.h>
+        #include <string.h>
+
+#if PHP_V8_API_VERSION >= 4004010
+class ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
+public:
+	virtual void* Allocate(size_t length) {
+		void* data = AllocateUninitialized(length);
+		return data == NULL ? data : memset(data, 0, length);
+	}
+	virtual void* AllocateUninitialized(size_t length) { return malloc(length); }
+	virtual void Free(void* data, size_t) { free(data); }
+};
+#endif
+
+        int main ()
+        {
+            v8::Platform *v8_platform = v8::platform::CreateDefaultPlatform();
+            v8::V8::InitializePlatform(v8_platform);
+            v8::V8::Initialize();
+
+#if PHP_V8_API_VERSION >= 4004044
+            static ArrayBufferAllocator array_buffer_allocator;
+            v8::Isolate::CreateParams create_params;
+            create_params.array_buffer_allocator = &array_buffer_allocator;
+
+            v8::Isolate::New(create_params);
+#else /* PHP_V8_API_VERSION < 4004044 */
+            v8::Isolate::New();
+#endif
+            return 0;
+        }
+    ], [
+        AC_MSG_RESULT([no])
+    ], [
+        AC_MSG_RESULT([yes])
+        AC_DEFINE([PHP_V8_USE_EXTERNAL_STARTUP_DATA], [1], [Whether V8 requires (and can be provided with custom versions of) external startup data])
+
+        SEARCH_PATH="$V8_DIR/lib $V8_DIR/share/v8"
+
+        AC_MSG_CHECKING([for natives_blob.bin])
+        SEARCH_FOR="natives_blob.bin"
+
+        for i in $SEARCH_PATH ; do
+          if test -r $i/$SEARCH_FOR; then
+            AC_MSG_RESULT([found ($i/$SEARCH_FOR)])
+            AC_DEFINE_UNQUOTED([PHP_V8_NATIVES_BLOB_PATH], "$i/$SEARCH_FOR", [Full path to natives_blob.bin file])
+            native_blob_found=1
+          fi
+        done
+
+        if test -z "$native_blob_found"; then
+          AC_MSG_RESULT([not found])
+          AC_MSG_ERROR([Please provide V8 native blob as needed])
+        fi
+
+        AC_MSG_CHECKING([for snapshot_blob.bin])
+        SEARCH_FOR="snapshot_blob.bin"
+
+        for i in $SEARCH_PATH ; do
+          if test -r $i/$SEARCH_FOR; then
+            AC_MSG_RESULT([found ($i/$SEARCH_FOR)])
+            AC_DEFINE_UNQUOTED([PHP_V8_SNAPSHOT_BLOB_PATH], "$i/$SEARCH_FOR", [Full path to snapshot_blob.bin file])
+            snapshot_blob_found=1
+          fi
+        done
+
+        if test -z "$snapshot_blob_found"; then
+          AC_MSG_RESULT([not found])
+          AC_MSG_ERROR([Please provide V8 snapshot blob as needed])
+        fi
+    ])
+  fi
+
+  AC_LANG_RESTORE
+  LIBS=$old_LIBS
+  LDFLAGS="$old_LDFLAGS $LDFLAGS_libplatform"
+  CPPFLAGS=$old_CPPFLAGS
+
+
   PHP_NEW_EXTENSION(v8js, [	\
     v8js_array_access.cc	\
     v8js.cc					\

tests/create_snapshot_basic.phpt

@@ -0,0 +1,32 @@
+--TEST--
+Test V8Js::createSnapshot() : Basic snapshot creation & re-use
+--SKIPIF--
+<?php
+require_once(dirname(__FILE__) . '/skipif.inc');
+
+if (!method_exists('V8Js', 'createSnapshot')) {
+    die('SKIP V8Js::createSnapshot not supported');
+}
+?>
+--FILE--
+<?php
+$doublifySource = <<<EOJS
+function doublify(x) {
+    return 2 * x;
+}
+EOJS;
+
+$snap = V8Js::createSnapshot($doublifySource);
+
+if (strlen($snap) > 0) {
+    var_dump("snapshot successfully created");
+}
+
+$v8 = new V8Js('PHP', array(), array(), true, $snap);
+$v8->executeString('var_dump(doublify(23));');
+?>
+===EOF===
+--EXPECT--
+string(29) "snapshot successfully created"
+int(46)
+===EOF===