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rpc: add context argument to EthSubscribe

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It's inconsistent not to pass it and most callers will
work with contexts anyway.
This commit is contained in:
Felix Lange
2016-08-05 13:24:48 +02:00
parent f5f042ffdc
commit e32925397b
3 changed files with 39 additions and 34 deletions
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59
rpc/client_example_test.go
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@ -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)
}
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
// 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
}
// 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
// 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())
// Subscribe to new blocks.
sub, err := client.EthSubscribe(ctx, subch, "newBlocks")
if err != nil {
fmt.Println("subscribe error:", err)
return
}
// 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())
}