Speed un reading from child process

Do the reading into a pre-allocated buffer to avoid mallocs in the inner
loop.

kitty/boss.py

@@ -21,7 +21,7 @@ from .char_grid import CharGrid
 from .keys import interpret_text_event, interpret_key_event
 from .utils import resize_pty, create_pty, sanitize_title
 from .fast_data_types import (
-    BRACKETED_PASTE_START, BRACKETED_PASTE_END, Screen, parse_bytes_dump, parse_bytes
+    BRACKETED_PASTE_START, BRACKETED_PASTE_END, Screen, read_bytes_dump, read_bytes
 )
 
 
@@ -56,7 +56,7 @@ class Boss(Thread):
         self.window, self.opts = window, opts
         self.screen = Screen(self)
         self.char_grid = CharGrid(self.screen, opts, window_width, window_height)
-        self.parse_bytes = partial(parse_bytes_dump, print) if args.dump_commands else parse_bytes
+        self.read_bytes = partial(read_bytes_dump, print) if args.dump_commands else read_bytes
         self.write_buf = memoryview(b'')
         glfw.glfwSetCharModsCallback(window, self.on_text_input)
         glfw.glfwSetKeyCallback(window, self.on_key)
@@ -201,16 +201,8 @@ class Boss(Thread):
     def read_ready(self):
         if self.shutting_down:
             return
-        try:
-            data = os.read(self.child_fd, 100 * io.DEFAULT_BUFFER_SIZE)
-        except BlockingIOError:
-            return
-        except EnvironmentError:
-            data = b''
-        if data:
-            self.parse_bytes(self.screen, data)
-        else:  # EOF
-            self.shutdown()
+        if self.read_bytes(self.screen, self.child_fd) is False:
+            self.shutdown()  # EOF
 
     def write_ready(self):
         if not self.shutting_down:

kitty/data-types.c

@@ -13,6 +13,8 @@ static PyMethodDef module_methods[] = {
     GL_METHODS
     {"parse_bytes", (PyCFunction)parse_bytes, METH_VARARGS, ""},
     {"parse_bytes_dump", (PyCFunction)parse_bytes_dump, METH_VARARGS, ""},
+    {"read_bytes", (PyCFunction)read_bytes, METH_VARARGS, ""},
+    {"read_bytes_dump", (PyCFunction)read_bytes_dump, METH_VARARGS, ""},
     {NULL, NULL, 0, NULL}        /* Sentinel */
 };
 

kitty/data-types.h

@@ -231,6 +231,7 @@ typedef struct {
 } SavepointBuffer;
 
 #define PARSER_BUF_SZ 8192
+#define READ_BUF_SZ (1024*1024)
 
 typedef struct {
     PyObject_HEAD
@@ -250,6 +251,7 @@ typedef struct {
     uint8_t parser_buf[PARSER_BUF_SZ];
     unsigned int parser_state, parser_text_start, parser_buf_pos;
     bool parser_has_pending_text;
+    uint8_t read_buf[READ_BUF_SZ];
 
 } Screen;
 PyTypeObject Screen_Type;
@@ -275,6 +277,8 @@ int init_SpriteMap(PyObject *);
 int init_ChangeTracker(PyObject *);
 int init_Screen(PyObject *);
 PyObject* create_256_color_table();
+PyObject* read_bytes_dump(PyObject UNUSED *, PyObject *);
+PyObject* read_bytes(PyObject UNUSED *, PyObject *);
 PyObject* parse_bytes_dump(PyObject UNUSED *, PyObject *);
 PyObject* parse_bytes(PyObject UNUSED *, PyObject *);
 uint16_t* translation_table(char);

kitty/parser.c

@@ -7,6 +7,8 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
 #include "data-types.h"
 #include "control-codes.h"
 
@@ -554,3 +556,34 @@ parse_bytes(PyObject UNUSED *self, PyObject *args) {
     _parse_bytes(screen, pybuf.buf, pybuf.len, dump_callback);
     Py_RETURN_NONE;
 }
+
+PyObject*
+#ifdef DUMP_COMMANDS
+read_bytes_dump(PyObject UNUSED *self, PyObject *args) {
+#else
+read_bytes(PyObject UNUSED *self, PyObject *args) {
+#endif
+    PyObject *dump_callback = NULL;
+    Py_ssize_t len;
+    Screen *screen;
+    int fd;
+#ifdef DUMP_COMMANDS
+    if (!PyArg_ParseTuple(args, "OOi", &dump_callback, &screen, &fd)) return NULL;
+#else
+    if (!PyArg_ParseTuple(args, "Oi", &screen, &fd)) return NULL;
+#endif
+
+    while(true) {
+        len = read(fd, screen->read_buf, READ_BUF_SZ);
+        if (len == -1) {
+            if (errno == EINTR) continue;
+            if (errno == EIO) { Py_RETURN_FALSE; }
+            return PyErr_SetFromErrno(PyExc_OSError);
+        }
+        break;
+    }
+    _parse_bytes(screen, screen->read_buf, len, dump_callback);
+    if(len > 0) { Py_RETURN_TRUE; }
+    Py_RETURN_FALSE;
+}
+