Ensure poller events do not overlap

talostrading · Apr 15, 2024 · 5ba3c3d · 5ba3c3d
1 parent e23717d
commit 5ba3c3d
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Showing 2 changed files with 24 additions and 0 deletions.
diff --git a/internal/poll_bsd.go b/internal/poll_bsd.go
@@ -4,6 +4,7 @@ package internal
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"sync"
 	"sync/atomic"
@@ -23,6 +24,17 @@ const (
 	PollerWriteEvent = -PollerEvent(syscall.EVFILT_WRITE)
 )
 
+func init() {
+	// The read and write events are used to set/unset bits in a Slot's event mask. We dispatch the read/write handler
+	// based on this event mask, so we must ensure they don't overlap.
+	if PollerReadEvent|PollerWriteEvent == PollerReadEvent || PollerReadEvent|PollerWriteEvent == PollerWriteEvent {
+		panic(fmt.Sprintf(
+			"PollerReadEvent=%d and PollerWriteEvent=%d overlap",
+			PollerReadEvent, PollerWriteEvent,
+		))
+	}
+}
+
 var _ Poller = &poller{}
 
 type poller struct {

diff --git a/internal/poll_linux.go b/internal/poll_linux.go
@@ -4,6 +4,7 @@ package internal
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"os"
 	"sync"
@@ -21,6 +22,17 @@ const (
 	PollerWriteEvent = PollerEvent(syscall.EPOLLOUT)
 )
 
+func init() {
+	// The read and write events are used to set/unset bits in a Slot's event mask. We dispatch the read/write handler
+	// based on this event mask, so we must ensure they don't overlap.
+	if PollerReadEvent|PollerWriteEvent == PollerReadEvent || PollerReadEvent|PollerWriteEvent == PollerWriteEvent {
+		panic(fmt.Sprintf(
+			"PollerReadEvent=%d and PollerWriteEvent=%d overlap",
+			PollerReadEvent, PollerWriteEvent,
+		))
+	}
+}
+
 type Event struct {
 	Mask uint32
 	Data [8]byte