Re-integrate FEAT_FILTERPIPE code

This feature was accidentally removed when doing the initial import from vim. It
makes vim use pipes instead of temporary files for filtering buffers through
shell commands.

I found that this was missing when looking for references of
SHELL_READ/SHELL_WRITE outside mch_call_shell`.

When `mch_call_shell` is reimplemented on top of libuv process management
facilities, pipes will always be used for communication with child processes so
it makes sense to enable the feature permanently.

1 files changed, 20 insertions, 8 deletions

diff --git a/src/os/event.c b/src/os/event.c
index 0a7d2c096c..ce630d5318 100644
--- a/src/os/event.c
+++ b/src/os/event.c
@@ -6,8 +6,10 @@
 #include "os/event.h"
 #include "os/input.h"
 
-static uv_timer_t timer_req;
+static uv_timer_t timer;
+static uv_prepare_t timer_prepare;
 static void timer_cb(uv_timer_t *handle, int);
+static void timer_prepare_cb(uv_prepare_t *, int);
 
 void event_init()
 {
@@ -15,7 +17,9 @@ void event_init()
   input_init();
   /* Timer to wake the event loop if a timeout argument is passed to
    * `event_poll` */
-  uv_timer_init(uv_default_loop(), &timer_req);
+  uv_timer_init(uv_default_loop(), &timer);
+  /* This prepare handle that actually starts the timer */
+  uv_prepare_init(uv_default_loop(), &timer_prepare);
 }
 
 /* Wait for some event */
@@ -33,10 +37,12 @@ bool event_poll(int32_t ms)
   timed_out = false;
 
   if (ms > 0) {
-    /* Timeout passed as argument, start the libuv timer to wake us up and 
-     * set our local flag */
-    timer_req.data = &timed_out;
-    uv_timer_start(&timer_req, timer_cb, ms, 0);
+    /* Timeout passed as argument to the timer */
+    timer.data = &timed_out;
+    /* We only start the timer after the loop is running, for that we
+     * use an prepare handle(pass the interval as data to it) */
+    timer_prepare.data = &ms;
+    uv_prepare_start(&timer_prepare, timer_prepare_cb);
   } else if (ms == 0) {
     /* 
      * For ms == 0, we need to do a non-blocking event poll by
@@ -58,10 +64,11 @@ bool event_poll(int32_t ms)
 
   input_stop();
 
-  if (!timed_out && ms > 0) {
+  if (ms > 0) {
     /* Timer event did not trigger, stop the watcher since we no longer
      * care about it */
-    uv_timer_stop(&timer_req);
+    uv_timer_stop(&timer);
+    uv_prepare_stop(&timer_prepare);
   }
 
   return input_ready();
@@ -72,3 +79,8 @@ static void timer_cb(uv_timer_t *handle, int status)
 {
   *((bool *)handle->data) = true;
 }
+
+static void timer_prepare_cb(uv_prepare_t *handle, int status)
+{
+  uv_timer_start(&timer, timer_cb, *(uint32_t *)handle->data, 0);
+}