Profiling suggested that on Linux sometimes over 10% of CPU time was being spent inside the systemtap probe entry points in the binding layer, even when the process was not actively being traced with the `stap` tool. That's why this commit makes it possible to use the *_ENABLED() macros and bail out early when we're not being traced, reducing the overhead of unused probes to (almost) zero. Said macros were already being generated by `dtrace -h` but were not usable because they rely on external definitions. To remedy that, we now generate the accompanying object files with `dtrace -G`. This commit includes a change to libuv that has been landed upstream in commit joyent/libuv@3c172ea.
* Change calls to String::New() and String::NewSymbol() to their respective one-byte, two-byte and UTF-8 counterparts. * Add a FIXED_ONE_BYTE_STRING macro that takes a string literal and turns it into a v8::Local<v8::String>. * Add helper functions that make v8::String::NewFromOneByte() easier to work with. Said function expects a `const uint8_t*` but almost every call site deals with `const char*` or `const unsigned char*`. Helps us avoid doing reinterpret_casts all over the place. * Code that handles file system paths keeps using UTF-8 for backwards compatibility reasons. At least now the use of UTF-8 is explicit. * Remove v8::String::NewSymbol() entirely. Almost all call sites were effectively minor de-optimizations. If you create a string only once, there is no point in making it a symbol. If you are create the same string repeatedly, it should probably be cached in a persistent handle.
This is a big commit that touches just about every file in the src/ directory. The V8 API has changed in significant ways. The most important changes are: * Binding functions take a const v8::FunctionCallbackInfo<T>& argument rather than a const v8::Arguments& argument. * Binding functions return void rather than v8::Handle<v8::Value>. The return value is returned with the args.GetReturnValue().Set() family of functions. * v8::Persistent<T> no longer derives from v8::Handle<T> and no longer allows you to directly dereference the object that the persistent handle points to. This means that the common pattern of caching oft-used JS values in a persistent handle no longer quite works, you first need to reconstruct a v8::Local<T> from the persistent handle with the Local<T>::New(isolate, persistent) factory method. A handful of (internal) convenience classes and functions have been added to make dealing with the new API a little easier. The most visible one is node::Cached<T>, which wraps a v8::Persistent<T> with some template sugar. It can hold arbitrary types but so far it's exclusively used for v8::Strings (which was by far the most commonly cached handle type.)
Check that _handle is an object before trying to read its `fd` property, avoids bogus values.
When using the DTrace/systemtap subsystems it would be helpful to actually have an fd associated with the requests and responses.
OSX and other DTrace implementations don't support dereferencing structs in probes. To accomodate that pass members from the struct as arguments so that DTrace is useful on those systems.
Update the api to pass node_isolate to all supported methods. Much thanks to Ben Noordhuis and his work in 51f6e6a.
All compile time warnings about using deprecated APIs have been suppressed by updating node's API. Though there are still many function calls that can accept Isolate, and still need to be updated. node_isolate had to be added as an extern variable in node.h and node_object_wrap.h Also a couple small fixes for Error handling. Before v8 3.16.6 the error stack message was lazily written when it was needed, which allowed you to change the message after instantiation. Then the stack would be written with the new message the first time it was accessed. Though that has changed. Now it creates the stack message on instantiation. So setting a different message afterwards won't be displayed. This is not a complete fix for the problem. Getting error without any message isn't very useful.