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rpc/dataconn/stream: Conn: handle concurrent Close calls + goroutine leak fix

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* Add Close() in closeState to identify the first closer
* Non-first closers get an error
* Reads and Writes from the Conn get an error if the conn was closed
  during the Read / Write was running
* The first closer starts _separate_ goroutine draining the c.frameReads channel
* The first closer then waits for the goroutine that fills c.frameReads
  to exit

refs 3bfe0c16d0
fixes #174

readFrames would block on `reads <-`
   but only after that would stream.Conn.readFrames close c.waitReadFramesDone
   which was too late because stream.Conn.Close would wait for c.waitReadFramesDone to be closed before draining the channel
                              ^^^^^^ (not frameconn.Conn, that closed successfully)

   195 @ 0x1032ae0 0x1006cab 0x1006c81 0x1006a65 0x15505be 0x155163e 0x1060bc1
           0x15505bd       github.com/zrepl/zrepl/rpc/dataconn/stream.readFrames+0x16d             github.com/zrepl/zrepl/rpc/dataconn/stream/stream.go:220
           0x155163d       github.com/zrepl/zrepl/rpc/dataconn/stream.(*Conn).readFrames+0xbd      github.com/zrepl/zrepl/rpc/dataconn/stream/stream_conn.go:71

   195 @ 0x1032ae0 0x10078c8 0x100789e 0x100758b 0x1552678 0x1557a4b 0x1556aec 0x1060bc1
           0x1552677       github.com/zrepl/zrepl/rpc/dataconn/stream.(*Conn).Close+0x77           github.com/zrepl/zrepl/rpc/dataconn/stream/stream_conn.go:191
           0x1557a4a       github.com/zrepl/zrepl/rpc/dataconn.(*Server).serveConn.func1+0x5a      github.com/zrepl/zrepl/rpc/dataconn/dataconn_server.go:93
           0x1556aeb       github.com/zrepl/zrepl/rpc/dataconn.(*Server).serveConn+0x87b           github.com/zrepl/zrepl/rpc/dataconn/dataconn_server.go:176
This commit is contained in:
Christian Schwarz
2019-09-13 14:48:18 +02:00
parent 8af824df41
commit a6b578b648
4 changed files with 147 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files
rpc/dataconn/stream/stream.go
+9 -2
View File
@@ -213,10 +213,17 @@ type readFrameResult struct {
err error
}
func readFrames(reads chan<- readFrameResult, c *heartbeatconn.Conn) {
for {
// readFrames reads from c into reads
// if a read from c encounters an error, noMoreReads is closed before sending the result into reads
func readFrames(reads chan<- readFrameResult, noMoreReads chan<- struct{}, c *heartbeatconn.Conn) {
// noMoreReads is already closed, don't re-close it
defer close(reads)
for { // only exits after a read error, make sure noMoreReads is closed
var r readFrameResult
r.f, r.err = c.ReadFrame()
if r.err != nil && noMoreReads != nil {
close(noMoreReads)
}
reads <- r
if r.err != nil {
return