rstream: Pass read count to read events

This is necessary to keep events in the same order received from the OS.

src/nvim/eval.c

@@ -21176,38 +21176,43 @@ static inline void process_job_event(TerminalJobData *data, ufunc_T *callback,
   on_job_event(&event_data);
 }
 
-static void on_job_stdout(Stream *stream, RBuffer *buf, void *job, bool eof)
+static void on_job_stdout(Stream *stream, RBuffer *buf, size_t count,
+    void *job, bool eof)
 {
   TerminalJobData *data = job;
-  on_job_output(stream, job, buf, eof, data->on_stdout, "stdout");
+  on_job_output(stream, job, buf, count, eof, data->on_stdout, "stdout");
 }
 
-static void on_job_stderr(Stream *stream, RBuffer *buf, void *job, bool eof)
+static void on_job_stderr(Stream *stream, RBuffer *buf, size_t count,
+    void *job, bool eof)
 {
   TerminalJobData *data = job;
-  on_job_output(stream, job, buf, eof, data->on_stderr, "stderr");
+  on_job_output(stream, job, buf, count, eof, data->on_stderr, "stderr");
 }
 
 static void on_job_output(Stream *stream, TerminalJobData *data, RBuffer *buf,
-    bool eof, ufunc_T *callback, const char *type)
+    size_t count, bool eof, ufunc_T *callback, const char *type)
 {
   if (eof) {
     return;
   }
 
-  RBUFFER_UNTIL_EMPTY(buf, ptr, len) {
-    // The order here matters, the terminal must receive the data first because
-    // process_job_event will modify the read buffer(convert NULs into NLs)
-    if (data->term) {
-      terminal_receive(data->term, ptr, len);
-    }
+  // stub variable, to keep reading consistent with the order of events, only
+  // consider the count parameter.
+  size_t r;
+  char *ptr = rbuffer_read_ptr(buf, &r);
 
-    if (callback) {
-      process_job_event(data, callback, type, ptr, len, 0);
-    }
-
-    rbuffer_consumed(buf, len);
+  // The order here matters, the terminal must receive the data first because
+  // process_job_event will modify the read buffer(convert NULs into NLs)
+  if (data->term) {
+    terminal_receive(data->term, ptr, count);
   }
+
+  if (callback) {
+    process_job_event(data, callback, type, ptr, count, 0);
+  }
+
+  rbuffer_consumed(buf, count);
 }
 
 static void on_process_exit(Process *proc, int status, void *d)

src/nvim/event/rstream.c

@@ -114,7 +114,7 @@ static void read_cb(uv_stream_t *uvstream, ssize_t cnt, const uv_buf_t *buf)
       // Read error or EOF, either way stop the stream and invoke the callback
       // with eof == true
       uv_read_stop(uvstream);
-      invoke_read_cb(stream, true);
+      invoke_read_cb(stream, 0, true);
     }
     return;
   }
@@ -124,7 +124,7 @@ static void read_cb(uv_stream_t *uvstream, ssize_t cnt, const uv_buf_t *buf)
   // Data was already written, so all we need is to update 'wpos' to reflect
   // the space actually used in the buffer.
   rbuffer_produced(stream->buffer, nread);
-  invoke_read_cb(stream, false);
+  invoke_read_cb(stream, nread, false);
 }
 
 // Called by the by the 'idle' handle to emulate a reading event
@@ -158,7 +158,7 @@ static void fread_idle_cb(uv_idle_t *handle)
 
   if (req.result <= 0) {
     uv_idle_stop(&stream->uv.idle);
-    invoke_read_cb(stream, true);
+    invoke_read_cb(stream, 0, true);
     return;
   }
 
@@ -166,19 +166,21 @@ static void fread_idle_cb(uv_idle_t *handle)
   size_t nread = (size_t) req.result;
   rbuffer_produced(stream->buffer, nread);
   stream->fpos += nread;
-  invoke_read_cb(stream, false);
+  invoke_read_cb(stream, nread, false);
 }
 
 static void read_event(void **argv)
 {
   Stream *stream = argv[0];
   if (stream->read_cb) {
-    bool eof = (uintptr_t)argv[1];
-    stream->read_cb(stream, stream->buffer, stream->data, eof);
+    size_t count = (uintptr_t)argv[1];
+    bool eof = (uintptr_t)argv[2];
+    stream->read_cb(stream, stream->buffer, count, stream->data, eof);
   }
 }
 
-static void invoke_read_cb(Stream *stream, bool eof)
+static void invoke_read_cb(Stream *stream, size_t count, bool eof)
 {
-  CREATE_EVENT(stream->events, read_event, 2, stream, (void *)(uintptr_t)eof);
+  CREATE_EVENT(stream->events, read_event, 3, stream,
+      (void *)(uintptr_t *)count, (void *)(uintptr_t)eof);
 }

src/nvim/event/stream.h

@@ -14,10 +14,14 @@ typedef struct stream Stream;
 ///
 /// @param stream The Stream instance
 /// @param rbuffer The associated RBuffer instance
+/// @param count Number of bytes to read. This must be respected if keeping
+///              the order of events is a requirement. This is because events
+///              may be queued and only processed later when more data is copied
+///              into to the buffer, so one read may starve another.
 /// @param data User-defined data
 /// @param eof If the stream reached EOF.
-typedef void (*stream_read_cb)(Stream *stream, RBuffer *buf, void *data,
-    bool eof);
+typedef void (*stream_read_cb)(Stream *stream, RBuffer *buf, size_t count,
+    void *data, bool eof);
 
 /// Type of function called when the Stream has information about a write
 /// request.

src/nvim/msgpack_rpc/channel.c

@@ -328,7 +328,8 @@ static void channel_from_stdio(void)
   wstream_init_fd(&loop, &channel->data.std.out, 1, 0, NULL);
 }
 
-static void forward_stderr(Stream *stream, RBuffer *rbuf, void *data, bool eof)
+static void forward_stderr(Stream *stream, RBuffer *rbuf, size_t count,
+    void *data, bool eof)
 {
   while (rbuffer_size(rbuf)) {
     char buf[256];
@@ -343,7 +344,8 @@ static void process_exit(Process *proc, int status, void *data)
   decref(data);
 }
 
-static void parse_msgpack(Stream *stream, RBuffer *rbuf, void *data, bool eof)
+static void parse_msgpack(Stream *stream, RBuffer *rbuf, size_t c, void *data,
+    bool eof)
 {
   Channel *channel = data;
   incref(channel);

src/nvim/os/input.c

@@ -316,7 +316,8 @@ static InbufPollResult inbuf_poll(int ms)
   return input_eof ? kInputEof : kInputNone;
 }
 
-static void read_cb(Stream *stream, RBuffer *buf, void *data, bool at_eof)
+static void read_cb(Stream *stream, RBuffer *buf, size_t c, void *data,
+    bool at_eof)
 {
   if (at_eof) {
     input_eof = true;

src/nvim/os/shell.c

@@ -298,7 +298,8 @@ static void dynamic_buffer_ensure(DynamicBuffer *buf, size_t desired)
   buf->data = xrealloc(buf->data, buf->cap);
 }
 
-static void system_data_cb(Stream *stream, RBuffer *buf, void *data, bool eof)
+static void system_data_cb(Stream *stream, RBuffer *buf, size_t count,
+    void *data, bool eof)
 {
   DynamicBuffer *dbuf = data;
 
@@ -308,7 +309,8 @@ static void system_data_cb(Stream *stream, RBuffer *buf, void *data, bool eof)
   dbuf->len += nread;
 }
 
-static void out_data_cb(Stream *stream, RBuffer *buf, void *data, bool eof)
+static void out_data_cb(Stream *stream, RBuffer *buf, size_t count, void *data,
+    bool eof)
 {
   size_t cnt;
   char *ptr = rbuffer_read_ptr(buf, &cnt);

src/nvim/tui/term_input.inl

@@ -208,7 +208,8 @@ static bool handle_forced_escape(TermInput *input)
 
 static void restart_reading(void **argv);
 
-static void read_cb(Stream *stream, RBuffer *buf, void *data, bool eof)
+static void read_cb(Stream *stream, RBuffer *buf, size_t c, void *data,
+    bool eof)
 {
   TermInput *input = data;