From bdd4629db462166cf811c284e5a75e124282a7a9 Mon Sep 17 00:00:00 2001
From: Dirk McCormick <dirkmdev@gmail.com>
Date: Tue, 10 Mar 2020 16:06:51 -0400
Subject: [PATCH] feat: timeout when peer doesnt respond to want-block

---
 bitswap.go                                  |  2 +-
 internal/messagequeue/donthavetimeoutmgr.go |  5 +++--
 internal/messagequeue/messagequeue.go       | 18 ++++++------------
 3 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/bitswap.go b/bitswap.go
index 1b59dcd0..a2bd56ca 100644
--- a/bitswap.go
+++ b/bitswap.go
@@ -125,7 +125,7 @@ func New(parent context.Context, network bsnet.BitSwapNetwork,
 	var wm *bswm.WantManager
 	// onDontHaveTimeout is called when a want-block is sent to a peer that
 	// has an old version of Bitswap that doesn't support DONT_HAVE messages,
-	// and no response is received within a timeout.
+	// or when no response is received within a timeout.
 	onDontHaveTimeout := func(p peer.ID, dontHaves []cid.Cid) {
 		// Simulate a DONT_HAVE message arriving to the WantManager
 		wm.ReceiveFrom(ctx, p, nil, nil, dontHaves)
diff --git a/internal/messagequeue/donthavetimeoutmgr.go b/internal/messagequeue/donthavetimeoutmgr.go
index ee7941b6..d1c6be58 100644
--- a/internal/messagequeue/donthavetimeoutmgr.go
+++ b/internal/messagequeue/donthavetimeoutmgr.go
@@ -11,7 +11,8 @@ import (
 
 const (
 	// dontHaveTimeout is used to simulate a DONT_HAVE when communicating with
-	// a peer whose Bitswap client doesn't support the DONT_HAVE response.
+	// a peer whose Bitswap client doesn't support the DONT_HAVE response,
+	// or when the peer takes too long to respond.
 	// If the peer doesn't respond to a want-block within the timeout, the
 	// local node assumes that the peer doesn't have the block.
 	dontHaveTimeout = 5 * time.Second
@@ -45,7 +46,7 @@ type pendingWant struct {
 
 // dontHaveTimeoutMgr pings the peer to measure latency. It uses the latency to
 // set a reasonable timeout for simulating a DONT_HAVE message for peers that
-// don't support DONT_HAVE
+// don't support DONT_HAVE or that take to long to respond.
 type dontHaveTimeoutMgr struct {
 	ctx                        context.Context
 	shutdown                   func()
diff --git a/internal/messagequeue/messagequeue.go b/internal/messagequeue/messagequeue.go
index 8e251889..922ab633 100644
--- a/internal/messagequeue/messagequeue.go
+++ b/internal/messagequeue/messagequeue.go
@@ -392,10 +392,8 @@ func (mq *MessageQueue) sendMessage() {
 	}
 
 	// Make sure the DONT_HAVE timeout manager has started
-	if !mq.sender.SupportsHave() {
-		// Note: Start is idempotent
-		mq.dhTimeoutMgr.Start()
-	}
+	// Note: Start is idempotent
+	mq.dhTimeoutMgr.Start()
 
 	// Convert want lists to a Bitswap Message
 	message, onSent := mq.extractOutgoingMessage(mq.sender.SupportsHave())
@@ -425,15 +423,11 @@ func (mq *MessageQueue) sendMessage() {
 	}
 }
 
-// If the peer is running an older version of Bitswap that doesn't support the
-// DONT_HAVE response, watch for timeouts on any want-blocks we sent the peer,
-// and if there is a timeout simulate a DONT_HAVE response.
+// If want-block times out, simulate a DONT_HAVE reponse.
+// This is necessary when making requests to peers running an older version of
+// Bitswap that doesn't support the DONT_HAVE response, and is also useful to
+// mitigate getting blocked by a peer that takes a long time to respond.
 func (mq *MessageQueue) simulateDontHaveWithTimeout(msg bsmsg.BitSwapMessage) {
-	// If the peer supports DONT_HAVE responses, we don't need to simulate
-	if mq.sender.SupportsHave() {
-		return
-	}
-
 	mq.wllock.Lock()
 
 	// Get the CID of each want-block that expects a DONT_HAVE response