2015-08-30 01:04:59 -07:00
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// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// package filters implements an ethereum filtering system for block,
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// transactions and log events.
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package filters
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import (
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/core"
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2015-08-30 01:19:10 -07:00
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"github.com/ethereum/go-ethereum/core/vm"
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2015-08-30 01:04:59 -07:00
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"github.com/ethereum/go-ethereum/event"
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)
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// FilterSystem manages filters that filter specific events such as
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// block, transaction and log events. The Filtering system can be used to listen
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2015-08-31 08:09:50 -07:00
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// for specific LOG events fired by the EVM (Ethereum Virtual Machine).
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type FilterSystem struct {
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filterMu sync.RWMutex
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filterId int
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filters map[int]*Filter
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created map[int]time.Time
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sub event.Subscription
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}
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// NewFilterSystem returns a newly allocated filter manager
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func NewFilterSystem(mux *event.TypeMux) *FilterSystem {
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fs := &FilterSystem{
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filters: make(map[int]*Filter),
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created: make(map[int]time.Time),
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}
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fs.sub = mux.Subscribe(
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//core.PendingBlockEvent{},
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core.ChainEvent{},
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core.TxPreEvent{},
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vm.Logs(nil),
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)
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go fs.filterLoop()
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return fs
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}
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// Stop quits the filter loop required for polling events
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func (fs *FilterSystem) Stop() {
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fs.sub.Unsubscribe()
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}
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// Add adds a filter to the filter manager
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func (fs *FilterSystem) Add(filter *Filter) (id int) {
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fs.filterMu.Lock()
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defer fs.filterMu.Unlock()
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id = fs.filterId
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fs.filters[id] = filter
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fs.created[id] = time.Now()
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fs.filterId++
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return id
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}
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// Remove removes a filter by filter id
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func (fs *FilterSystem) Remove(id int) {
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fs.filterMu.Lock()
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defer fs.filterMu.Unlock()
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delete(fs.filters, id)
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delete(fs.created, id)
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}
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// Get retrieves a filter installed using Add The filter may not be modified.
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func (fs *FilterSystem) Get(id int) *Filter {
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fs.filterMu.RLock()
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defer fs.filterMu.RUnlock()
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return fs.filters[id]
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}
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// filterLoop waits for specific events from ethereum and fires their handlers
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// when the filter matches the requirements.
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func (fs *FilterSystem) filterLoop() {
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for event := range fs.sub.Chan() {
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switch ev := event.Data.(type) {
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case core.ChainEvent:
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fs.filterMu.RLock()
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for id, filter := range fs.filters {
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if filter.BlockCallback != nil && fs.created[id].Before(event.Time) {
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filter.BlockCallback(ev.Block, ev.Logs)
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}
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}
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fs.filterMu.RUnlock()
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case core.TxPreEvent:
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fs.filterMu.RLock()
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for id, filter := range fs.filters {
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if filter.TransactionCallback != nil && fs.created[id].Before(event.Time) {
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filter.TransactionCallback(ev.Tx)
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}
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}
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fs.filterMu.RUnlock()
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case vm.Logs:
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fs.filterMu.RLock()
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for id, filter := range fs.filters {
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if filter.LogsCallback != nil && fs.created[id].Before(event.Time) {
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msgs := filter.FilterLogs(ev)
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if len(msgs) > 0 {
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filter.LogsCallback(msgs)
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}
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}
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}
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fs.filterMu.RUnlock()
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}
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}
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}
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