From e32925397b3110f6dd5e18c79f6641bd2a55776f Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Fri, 5 Aug 2016 13:24:48 +0200 Subject: [PATCH] rpc: add context argument to EthSubscribe It's inconsistent not to pass it and most callers will work with contexts anyway. --- rpc/client.go | 6 ++-- rpc/client_example_test.go | 57 +++++++++++++++++++++----------------- rpc/client_test.go | 8 +++--- 3 files changed, 38 insertions(+), 33 deletions(-) diff --git a/rpc/client.go b/rpc/client.go index 6846e1dda..34a3b7831 100644 --- a/rpc/client.go +++ b/rpc/client.go @@ -354,12 +354,14 @@ func (c *Client) BatchCallContext(ctx context.Context, b []BatchElem) error { // sent to the given channel. The element type of the channel must match the // expected type of content returned by the subscription. // +// The context argument cancels the RPC request that sets up the subscription but has no +// effect on the subscription after EthSubscribe has returned. // // Slow subscribers will be dropped eventually. Client buffers up to 8000 notifications // before considering the subscriber dead. The subscription Err channel will receive // ErrSubscriptionQueueOverflow. Use a sufficiently large buffer on the channel or ensure // that the channel usually has at least one reader to prevent this issue. -func (c *Client) EthSubscribe(channel interface{}, args ...interface{}) (*ClientSubscription, error) { +func (c *Client) EthSubscribe(ctx context.Context, channel interface{}, args ...interface{}) (*ClientSubscription, error) { // Check type of channel first. chanVal := reflect.ValueOf(channel) if chanVal.Kind() != reflect.Chan || chanVal.Type().ChanDir()&reflect.SendDir == 0 { @@ -381,8 +383,6 @@ func (c *Client) EthSubscribe(channel interface{}, args ...interface{}) (*Client resp: make(chan *jsonrpcMessage), sub: newClientSubscription(c, chanVal), } - ctx, cancel := context.WithTimeout(context.Background(), subscribeTimeout) - defer cancel() // Send the subscription request. // The arrival and validity of the response is signaled on sub.quit. diff --git a/rpc/client_example_test.go b/rpc/client_example_test.go index 84b4b67bb..3462b3685 100644 --- a/rpc/client_example_test.go +++ b/rpc/client_example_test.go @@ -22,6 +22,7 @@ import ( "time" "github.com/ethereum/go-ethereum/rpc" + "golang.org/x/net/context" ) // In this example, our client whishes to track the latest 'block number' @@ -41,7 +42,16 @@ func ExampleClientSubscription() { // Connect the client. client, _ := rpc.Dial("ws://127.0.0.1:8485") subch := make(chan Block) - go subscribeBlocks(client, subch) + + // Ensure that subch receives the latest block. + go func() { + for i := 0; ; i++ { + if i > 0 { + time.Sleep(2 * time.Second) + } + subscribeBlocks(client, subch) + } + }() // Print events from the subscription as they arrive. for block := range subch { @@ -52,32 +62,27 @@ func ExampleClientSubscription() { // subscribeBlocks runs in its own goroutine and maintains // a subscription for new blocks. func subscribeBlocks(client *rpc.Client, subch chan Block) { - for i := 0; ; i++ { - if i > 0 { - time.Sleep(2 * time.Second) - } - - // Subscribe to new blocks. - sub, err := client.EthSubscribe(subch, "newBlocks") - if err == rpc.ErrClientQuit { - return // Stop reconnecting if the client was closed. - } else if err != nil { - fmt.Println("subscribe error:", err) - continue - } + ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) + defer cancel() - // The connection is established now. - // Update the channel with the current block. - var lastBlock Block - if err := client.Call(&lastBlock, "eth_getBlockByNumber", "latest"); err != nil { - fmt.Println("can't get latest block:", err) - continue - } - subch <- lastBlock + // Subscribe to new blocks. + sub, err := client.EthSubscribe(ctx, subch, "newBlocks") + if err != nil { + fmt.Println("subscribe error:", err) + return + } - // The subscription will deliver events to the channel. Wait for the - // subscription to end for any reason, then loop around to re-establish - // the connection. - fmt.Println("connection lost: ", <-sub.Err()) + // The connection is established now. + // Update the channel with the current block. + var lastBlock Block + if err := client.CallContext(ctx, &lastBlock, "eth_getBlockByNumber", "latest"); err != nil { + fmt.Println("can't get latest block:", err) + return } + subch <- lastBlock + + // The subscription will deliver events to the channel. Wait for the + // subscription to end for any reason, then loop around to re-establish + // the connection. + fmt.Println("connection lost: ", <-sub.Err()) } diff --git a/rpc/client_test.go b/rpc/client_test.go index 424d7f5bc..476c8c6f3 100644 --- a/rpc/client_test.go +++ b/rpc/client_test.go @@ -215,7 +215,7 @@ func TestClientSubscribeInvalidArg(t *testing.T) { t.Error(string(buf)) } }() - client.EthSubscribe(arg, "foo_bar") + client.EthSubscribe(context.Background(), arg, "foo_bar") } check(true, nil) check(true, 1) @@ -233,7 +233,7 @@ func TestClientSubscribe(t *testing.T) { nc := make(chan int) count := 10 - sub, err := client.EthSubscribe(nc, "someSubscription", count, 0) + sub, err := client.EthSubscribe(context.Background(), nc, "someSubscription", count, 0) if err != nil { t.Fatal("can't subscribe:", err) } @@ -275,7 +275,7 @@ func TestClientSubscribeClose(t *testing.T) { err error ) go func() { - sub, err = client.EthSubscribe(nc, "hangSubscription", 999) + sub, err = client.EthSubscribe(context.Background(), nc, "hangSubscription", 999) errc <- err }() @@ -311,7 +311,7 @@ func TestClientNotificationStorm(t *testing.T) { // Subscribe on the server. It will start sending many notifications // very quickly. nc := make(chan int) - sub, err := client.EthSubscribe(nc, "someSubscription", count, 0) + sub, err := client.EthSubscribe(ctx, nc, "someSubscription", count, 0) if err != nil { t.Fatal("can't subscribe:", err) } -- GitLab