1 files changed, 145 insertions, 0 deletions
diff --git a/eth/filters/filter_system.go b/eth/filters/filter_system.go
new file mode 100644
index 000000000..ae6093525
--- /dev/null
+++ b/eth/filters/filter_system.go
@@ -0,0 +1,145 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// package filters implements an ethereum filtering system for block,
+// transactions and log events.
+package filters
+
+import (
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/event"
+)
+
+// FilterSystem manages filters that filter specific events such as
+// block, transaction and log events. The Filtering system can be used to listen
+// for specific LOG events fired by the EVM (Ethereum Virtual Machine).
+type FilterSystem struct {
+	eventMux *event.TypeMux
+
+	filterMu sync.RWMutex
+	filterId int
+	filters  map[int]*Filter
+	created  map[int]time.Time
+
+	quit chan struct{}
+}
+
+// NewFilterSystem returns a newly allocated filter manager
+func NewFilterSystem(mux *event.TypeMux) *FilterSystem {
+	fs := &FilterSystem{
+		eventMux: mux,
+		filters:  make(map[int]*Filter),
+		created:  make(map[int]time.Time),
+	}
+	go fs.filterLoop()
+	return fs
+}
+
+// Stop quits the filter loop required for polling events
+func (fs *FilterSystem) Stop() {
+	close(fs.quit)
+}
+
+// Add adds a filter to the filter manager
+func (fs *FilterSystem) Add(filter *Filter) (id int) {
+	fs.filterMu.Lock()
+	defer fs.filterMu.Unlock()
+	id = fs.filterId
+	fs.filters[id] = filter
+	fs.created[id] = time.Now()
+	fs.filterId++
+
+	return id
+}
+
+// Remove removes a filter by filter id
+func (fs *FilterSystem) Remove(id int) {
+	fs.filterMu.Lock()
+	defer fs.filterMu.Unlock()
+
+	delete(fs.filters, id)
+	delete(fs.created, id)
+}
+
+// Get retrieves a filter installed using Add The filter may not be modified.
+func (fs *FilterSystem) Get(id int) *Filter {
+	fs.filterMu.RLock()
+	defer fs.filterMu.RUnlock()
+
+	return fs.filters[id]
+}
+
+// filterLoop waits for specific events from ethereum and fires their handlers
+// when the filter matches the requirements.
+func (fs *FilterSystem) filterLoop() {
+	// Subscribe to events
+	eventCh := fs.eventMux.Subscribe(
+		//core.PendingBlockEvent{},
+		core.ChainEvent{},
+		core.TxPreEvent{},
+		vm.Logs(nil),
+	).Chan()
+
+out:
+	for {
+		select {
+		case <-fs.quit:
+			break out
+		case event, ok := <-eventCh:
+			if !ok {
+				// Event subscription closed, set the channel to nil to stop spinning
+				eventCh = nil
+				continue
+			}
+			// A real event arrived, notify the registered filters
+			switch ev := event.Data.(type) {
+			case core.ChainEvent:
+				fs.filterMu.RLock()
+				for id, filter := range fs.filters {
+					if filter.BlockCallback != nil && fs.created[id].Before(event.Time) {
+						filter.BlockCallback(ev.Block, ev.Logs)
+					}
+				}
+				fs.filterMu.RUnlock()
+
+			case core.TxPreEvent:
+				fs.filterMu.RLock()
+				for id, filter := range fs.filters {
+					if filter.TransactionCallback != nil && fs.created[id].Before(event.Time) {
+						filter.TransactionCallback(ev.Tx)
+					}
+				}
+				fs.filterMu.RUnlock()
+
+			case vm.Logs:
+				fs.filterMu.RLock()
+				for id, filter := range fs.filters {
+					if filter.LogsCallback != nil && fs.created[id].Before(event.Time) {
+						msgs := filter.FilterLogs(ev)
+						if len(msgs) > 0 {
+							filter.LogsCallback(msgs)
+						}
+					}
+				}
+				fs.filterMu.RUnlock()
+			}
+		}
+	}
+}