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Merge pull request #17732 from karalabe/faucet-caching

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cmd/faucet: cache internal state, avoid sync-trashing les
This commit is contained in:
Péter Szilágyi 2018-09-21 14:20:46 +03:00 committed by GitHub
commit 06d40d37b8
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 68 additions and 46 deletions
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114
cmd/faucet/faucet.go
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@ -199,6 +199,8 @@ type faucet struct {
keystore *keystore.KeyStore // Keystore containing the single signer
account accounts.Account // Account funding user faucet requests
head *types.Header // Current head header of the faucet
balance *big.Int // Current balance of the faucet
nonce uint64 // Current pending nonce of the faucet
price *big.Int // Current gas price to issue funds with
@ -324,33 +326,30 @@ func (f *faucet) apiHandler(conn *websocket.Conn) {
nonce uint64
err error
)
for {
// Attempt to retrieve the stats, may error on no faucet connectivity
ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
head, err = f.client.HeaderByNumber(ctx, nil)
if err == nil {
balance, err = f.client.BalanceAt(ctx, f.account.Address, head.Number)
if err == nil {
nonce, err = f.client.NonceAt(ctx, f.account.Address, nil)
}
for head == nil || balance == nil {
// Retrieve the current stats cached by the faucet
f.lock.RLock()
if f.head != nil {
head = types.CopyHeader(f.head)
}
cancel()
if f.balance != nil {
balance = new(big.Int).Set(f.balance)
}
nonce = f.nonce
f.lock.RUnlock()
// If stats retrieval failed, wait a bit and retry
if err != nil {
if err = sendError(conn, errors.New("Faucet offline: "+err.Error())); err != nil {
if head == nil || balance == nil {
// Report the faucet offline until initial stats are ready
if err = sendError(conn, errors.New("Faucet offline")); err != nil {
log.Warn("Failed to send faucet error to client", "err", err)
return
}
time.Sleep(3 * time.Second)
continue
}
// Initial stats reported successfully, proceed with user interaction
break
}
// Send over the initial stats and the latest header
if err = send(conn, map[string]interface{}{
"funds": balance.Div(balance, ether),
"funds": new(big.Int).Div(balance, ether),
"funded": nonce,
"peers": f.stack.Server().PeerCount(),
"requests": f.reqs,
@ -520,6 +519,47 @@ func (f *faucet) apiHandler(conn *websocket.Conn) {
}
}
// refresh attempts to retrieve the latest header from the chain and extract the
// associated faucet balance and nonce for connectivity caching.
func (f *faucet) refresh(head *types.Header) error {
// Ensure a state update does not run for too long
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
// If no header was specified, use the current chain head
var err error
if head == nil {
if head, err = f.client.HeaderByNumber(ctx, nil); err != nil {
return err
}
}
// Retrieve the balance, nonce and gas price from the current head
var (
balance *big.Int
nonce uint64
price *big.Int
)
if balance, err = f.client.BalanceAt(ctx, f.account.Address, head.Number); err != nil {
return err
}
if nonce, err = f.client.NonceAt(ctx, f.account.Address, head.Number); err != nil {
return err
}
if price, err = f.client.SuggestGasPrice(ctx); err != nil {
return err
}
// Everything succeeded, update the cached stats and eject old requests
f.lock.Lock()
f.head, f.balance = head, balance
f.price, f.nonce = price, nonce
for len(f.reqs) > 0 && f.reqs[0].Tx.Nonce() < f.nonce {
f.reqs = f.reqs[1:]
}
f.lock.Unlock()
return nil
}
// loop keeps waiting for interesting events and pushes them out to connected
// websockets.
func (f *faucet) loop() {
@ -537,45 +577,27 @@ func (f *faucet) loop() {
go func() {
for head := range update {
// New chain head arrived, query the current stats and stream to clients
var (
balance *big.Int
nonce uint64
price *big.Int
err error
)
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
balance, err = f.client.BalanceAt(ctx, f.account.Address, head.Number)
if err == nil {
nonce, err = f.client.NonceAt(ctx, f.account.Address, nil)
if err == nil {
price, err = f.client.SuggestGasPrice(ctx)
}
timestamp := time.Unix(head.Time.Int64(), 0)
if time.Since(timestamp) > time.Hour {
log.Warn("Skipping faucet refresh, head too old", "number", head.Number, "hash", head.Hash(), "age", common.PrettyAge(timestamp))
continue
}
cancel()
// If querying the data failed, try for the next block
if err != nil {
if err := f.refresh(head); err != nil {
log.Warn("Failed to update faucet state", "block", head.Number, "hash", head.Hash(), "err", err)
continue
} else {
log.Info("Updated faucet state", "block", head.Number, "hash", head.Hash(), "balance", balance, "nonce", nonce, "price", price)
}
// Faucet state retrieved, update locally and send to clients
balance = new(big.Int).Div(balance, ether)
f.lock.Lock()
f.price, f.nonce = price, nonce
for len(f.reqs) > 0 && f.reqs[0].Tx.Nonce() < f.nonce {
f.reqs = f.reqs[1:]
}
f.lock.Unlock()
f.lock.RLock()
log.Info("Updated faucet state", "number", head.Number, "hash", head.Hash(), "age", common.PrettyAge(timestamp), "balance", f.balance, "nonce", f.nonce, "price", f.price)
balance := new(big.Int).Div(f.balance, ether)
peers := f.stack.Server().PeerCount()
for _, conn := range f.conns {
if err := send(conn, map[string]interface{}{
"funds": balance,
"funded": f.nonce,
"peers": f.stack.Server().PeerCount(),
"peers": peers,
"requests": f.reqs,
}, time.Second); err != nil {
log.Warn("Failed to send stats to client", "err", err)