Support zero-copy data in libdeno.send(). (#838)

This is a large API refactor of deno.h which replaces
deno_send() and deno_set_response() with deno_respond().
It also adds a req_id parameter to the deno_recv_cb.

Make writeFile/writeFileSync use it.

1 files changed, 24 insertions, 18 deletions

diff --git a/libdeno/deno.h b/libdeno/deno.h
index 90edca3d9..b0248b7ad 100644
--- a/libdeno/deno.h
+++ b/libdeno/deno.h
@@ -20,9 +20,11 @@ typedef struct {
 struct deno_s;
 typedef struct deno_s Deno;
 
-// A callback to receive a message from deno.send javascript call.
-// buf is valid only for the lifetime of the call.
-typedef void (*deno_recv_cb)(Deno* d, deno_buf buf);
+// A callback to receive a message from a libdeno.send() javascript call.
+// control_buf is valid for only for the lifetime of this callback.
+// data_buf is valid until deno_respond() is called.
+typedef void (*deno_recv_cb)(Deno* d, int32_t req_id, deno_buf control_buf,
+                             deno_buf data_buf);
 
 void deno_init();
 const char* deno_v8_version();
@@ -39,21 +41,25 @@ void* deno_get_data(Deno*);
 // 0 = fail, 1 = success
 int deno_execute(Deno* d, const char* js_filename, const char* js_source);
 
-// Routes message to the javascript callback set with deno.recv(). A false
-// return value indicates error. Check deno_last_exception() for exception text.
-// 0 = fail, 1 = success
-// After calling deno_send(), the caller no longer owns `buf` and must not use
-// it; deno_send() is responsible for releasing it's memory.
-// TODO(piscisaureus) In C++ and/or Rust, use a smart pointer or similar to
-// enforce this rule.
-int deno_send(Deno* d, deno_buf buf);
-
-// Call this inside a deno_recv_cb to respond synchronously to messages.
-// If this is not called during the life time of a deno_recv_cb callback
-// the deno.send() call in javascript will return null.
-// After calling deno_set_response(), the caller no longer owns `buf` and must
-// not access it; deno_set_response() is responsible for releasing it's memory.
-void deno_set_response(Deno* d, deno_buf buf);
+// deno_respond sends up to one message back for every deno_recv_cb made.
+//
+// If this is called during deno_recv_cb, the issuing libdeno.send() in
+// javascript will synchronously return the specified buf as an ArrayBuffer (or
+// null if buf is empty).
+//
+// If this is called after deno_recv_cb has returned, the deno_respond
+// will call into the JS callback specified by libdeno.recv().
+//
+// (Ideally, but not currently: After calling deno_respond(), the caller no
+// longer owns `buf` and must not use it; deno_respond() is responsible for
+// releasing its memory.)
+//
+// Calling this function more than once with the same req_id will result in
+// an error.
+//
+// A non-zero return value, means a JS exception was encountered during the
+// libdeno.recv() callback. Check deno_last_exception() for exception text.
+int deno_respond(Deno* d, int32_t req_id, deno_buf buf);
 
 const char* deno_last_exception(Deno* d);