Merge pull request #424 from junliurs/feat/support-riscv64-epoll

feat: add riscv64 epoll support

Author: junliurs

sys_epoll_linux_other.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build linux && !arm64 && !amd64
+//go:build linux && !arm64 && !amd64 && !riscv64
 
 package netpoll
 

sys_epoll_linux_riscv64.go

@@ -0,0 +1,40 @@
+// Copyright 2022 CloudWeGo Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build linux && riscv64
+
+package netpoll
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// EpollWait implements epoll_wait.
+// riscv64 only provides SYS_EPOLL_PWAIT (no SYS_EPOLL_WAIT).
+func EpollWait(epfd int, events []epollevent, msec int) (n int, err error) {
+	var r0 uintptr
+	_p0 := unsafe.Pointer(&events[0])
+	if msec == 0 {
+		// When timeout is 0 (non-blocking poll), use RawSyscall6 to avoid the overhead
+		// of scheduler coordination (entersyscall/exitsyscall) since it won't block.
+		r0, _, err = syscall.RawSyscall6(syscall.SYS_EPOLL_PWAIT, uintptr(epfd), uintptr(_p0), uintptr(len(events)), 0, 0, 0)
+	} else {
+		r0, _, err = syscall.Syscall6(syscall.SYS_EPOLL_PWAIT, uintptr(epfd), uintptr(_p0), uintptr(len(events)), uintptr(msec), 0, 0)
+	}
+	if err == syscall.Errno(0) {
+		err = nil
+	}
+	return int(r0), err
+}