fix wait 0wait

5 files changed, 30 insertions, 5 deletions

diff --git a/xmake/core/base/fwatcher.lua b/xmake/core/base/fwatcher.lua
index 9fc04722e..e05baa584 100644
--- a/xmake/core/base/fwatcher.lua
+++ b/xmake/core/base/fwatcher.lua
@@ -93,7 +93,7 @@ end
 
 -- wait event
 --
--- @param timeout   the timeout
+-- @param timeout   the timeout in milliseconds, -1 for infinite, 0 to check without waiting
 --
 -- @return          ok, event, e.g {type = fwatcher.ET_MODIFY, path = "/tmp"}
 --
diff --git a/xmake/core/base/pipe.lua b/xmake/core/base/pipe.lua
index 137f9c779..9a896afba 100644
--- a/xmake/core/base/pipe.lua
+++ b/xmake/core/base/pipe.lua
@@ -235,7 +235,7 @@ end
 -- wait pipe events
 --
 -- @param events    the events to wait, e.g. pipe.EV_READ, pipe.EV_WRITE
--- @param timeout   the timeout in milliseconds, -1 for infinite
+-- @param timeout   the timeout in milliseconds, -1 for infinite, 0 to check without waiting
 -- @return          the received events, or 0 on timeout
 --
 function _instance:wait(events, timeout)
diff --git a/xmake/core/base/process.lua b/xmake/core/base/process.lua
index 35b0b15b7..0c4c509b0 100644
--- a/xmake/core/base/process.lua
+++ b/xmake/core/base/process.lua
@@ -81,9 +81,9 @@ end
 
 -- wait subprocess
 --
--- @param timeout   the timeout
+-- @param timeout   the timeout in milliseconds, -1 for infinite, 0 to check without waiting
 --
--- @return          ok, status
+-- @return          ok, status, e.g. -1 on error, 0 on timeout, 1 on exited
 --
 function _subprocess:wait(timeout)
 
diff --git a/xmake/core/base/scheduler.lua b/xmake/core/base/scheduler.lua
index 4ae8d74e0..f936f1d8f 100644
--- a/xmake/core/base/scheduler.lua
+++ b/xmake/core/base/scheduler.lua
@@ -982,6 +982,15 @@ function scheduler:poller_wait(obj, events, timeout)
         end
     end
 
+    -- no events yet? return immediately if timeout is zero
+    --
+    -- @note we save the waiting events, so the poller caches the events when they
+    -- arrive and the next wait returns them immediately
+    if timeout == 0 then
+        pollerdata.poller_events_wait = events_wait
+        return 0
+    end
+
     -- register timeout task to timer
     local timer_task = nil
     if timeout > 0 then
@@ -1053,6 +1062,14 @@ function scheduler:poller_waitproc(obj, timeout)
         return -1, errors
     end
 
+    -- has not exited yet? return immediately if timeout is zero
+    --
+    -- @note we have inserted it into the poller, so its exit status is still saved
+    -- as a pending status when it exits later, and the next wait returns it immediately
+    if timeout == 0 then
+        return 0
+    end
+
     -- register timeout task to timer
     local timer_task = nil
     if timeout > 0 then
@@ -1123,6 +1140,14 @@ function scheduler:poller_waitfs(obj, timeout)
         return -1, errors
     end
 
+    -- no event yet? return immediately if timeout is zero
+    --
+    -- @note we have inserted it into the poller, so the next event is still saved
+    -- as a pending status when it arrives, and the next wait returns it immediately
+    if timeout == 0 then
+        return 0
+    end
+
     -- register timeout task to timer
     local timer_task = nil
     if timeout > 0 then
diff --git a/xmake/core/base/socket.lua b/xmake/core/base/socket.lua
index 393edd199..fbe1fea10 100644
--- a/xmake/core/base/socket.lua
+++ b/xmake/core/base/socket.lua
@@ -675,7 +675,7 @@ end
 -- wait for socket events
 --
 -- @param events    the events to wait, e.g. socket.EV_RECV, socket.EV_SEND
--- @param timeout   the timeout in milliseconds, -1 for infinite
+-- @param timeout   the timeout in milliseconds, -1 for infinite, 0 to check without waiting
 -- @return          the received events, or 0 on timeout
 --
 function _instance:wait(events, timeout)