TUN-7373: Streaming logs override for same actor

To help accommodate web browser interactions with websockets, when a
streaming logs session is requested for the same actor while already
serving a session for that user in a separate request, the original
request will be closed and the new request start streaming logs
instead. This should help with rogue sessions holding on for too long
with no client on the other side (before idle timeout or connection
close).

vendor/golang.org/x/tools/go/ast/inspector/inspector.go

@@ -53,10 +53,13 @@ func New(files []*ast.File) *Inspector {
 // of an ast.Node during a traversal.
 type event struct {
 	node  ast.Node
-	typ   uint64 // typeOf(node)
-	index int    // 1 + index of corresponding pop event, or 0 if this is a pop
+	typ   uint64 // typeOf(node) on push event, or union of typ strictly between push and pop events on pop events
+	index int    // index of corresponding push or pop event
 }
 
+// TODO: Experiment with storing only the second word of event.node (unsafe.Pointer).
+// Type can be recovered from the sole bit in typ.
+
 // Preorder visits all the nodes of the files supplied to New in
 // depth-first order. It calls f(n) for each node n before it visits
 // n's children.
@@ -72,10 +75,17 @@ func (in *Inspector) Preorder(types []ast.Node, f func(ast.Node)) {
 	mask := maskOf(types)
 	for i := 0; i < len(in.events); {
 		ev := in.events[i]
-		if ev.typ&mask != 0 {
-			if ev.index > 0 {
+		if ev.index > i {
+			// push
+			if ev.typ&mask != 0 {
 				f(ev.node)
 			}
+			pop := ev.index
+			if in.events[pop].typ&mask == 0 {
+				// Subtrees do not contain types: skip them and pop.
+				i = pop + 1
+				continue
+			}
 		}
 		i++
 	}
@@ -94,15 +104,24 @@ func (in *Inspector) Nodes(types []ast.Node, f func(n ast.Node, push bool) (proc
 	mask := maskOf(types)
 	for i := 0; i < len(in.events); {
 		ev := in.events[i]
-		if ev.typ&mask != 0 {
-			if ev.index > 0 {
-				// push
+		if ev.index > i {
+			// push
+			pop := ev.index
+			if ev.typ&mask != 0 {
 				if !f(ev.node, true) {
-					i = ev.index // jump to corresponding pop + 1
+					i = pop + 1 // jump to corresponding pop + 1
 					continue
 				}
-			} else {
-				// pop
+			}
+			if in.events[pop].typ&mask == 0 {
+				// Subtrees do not contain types: skip them.
+				i = pop
+				continue
+			}
+		} else {
+			// pop
+			push := ev.index
+			if in.events[push].typ&mask != 0 {
 				f(ev.node, false)
 			}
 		}
@@ -119,19 +138,26 @@ func (in *Inspector) WithStack(types []ast.Node, f func(n ast.Node, push bool, s
 	var stack []ast.Node
 	for i := 0; i < len(in.events); {
 		ev := in.events[i]
-		if ev.index > 0 {
+		if ev.index > i {
 			// push
+			pop := ev.index
 			stack = append(stack, ev.node)
 			if ev.typ&mask != 0 {
 				if !f(ev.node, true, stack) {
-					i = ev.index
+					i = pop + 1
 					stack = stack[:len(stack)-1]
 					continue
 				}
 			}
+			if in.events[pop].typ&mask == 0 {
+				// Subtrees does not contain types: skip them.
+				i = pop
+				continue
+			}
 		} else {
 			// pop
-			if ev.typ&mask != 0 {
+			push := ev.index
+			if in.events[push].typ&mask != 0 {
 				f(ev.node, false, stack)
 			}
 			stack = stack[:len(stack)-1]
@@ -157,25 +183,31 @@ func traverse(files []*ast.File) []event {
 	events := make([]event, 0, capacity)
 
 	var stack []event
+	stack = append(stack, event{}) // include an extra event so file nodes have a parent
 	for _, f := range files {
 		ast.Inspect(f, func(n ast.Node) bool {
 			if n != nil {
 				// push
 				ev := event{
 					node:  n,
-					typ:   typeOf(n),
+					typ:   0,           // temporarily used to accumulate type bits of subtree
 					index: len(events), // push event temporarily holds own index
 				}
 				stack = append(stack, ev)
 				events = append(events, ev)
 			} else {
 				// pop
-				ev := stack[len(stack)-1]
-				stack = stack[:len(stack)-1]
+				top := len(stack) - 1
+				ev := stack[top]
+				typ := typeOf(ev.node)
+				push := ev.index
+				parent := top - 1
 
-				events[ev.index].index = len(events) + 1 // make push refer to pop
+				events[push].typ = typ            // set type of push
+				stack[parent].typ |= typ | ev.typ // parent's typ contains push and pop's typs.
+				events[push].index = len(events)  // make push refer to pop
 
-				ev.index = 0 // turn ev into a pop event
+				stack = stack[:top]
 				events = append(events, ev)
 			}
 			return true

vendor/golang.org/x/tools/go/ast/inspector/typeof.go

@@ -11,6 +11,7 @@ package inspector
 
 import (
 	"go/ast"
+	"math"
 
 	"golang.org/x/tools/internal/typeparams"
 )
@@ -218,7 +219,7 @@ func typeOf(n ast.Node) uint64 {
 
 func maskOf(nodes []ast.Node) uint64 {
 	if nodes == nil {
-		return 1<<64 - 1 // match all node types
+		return math.MaxUint64 // match all node types
 	}
 	var mask uint64
 	for _, n := range nodes {