From f7a71996fbbe9cea4445600ffa3c232a6cf42803 Mon Sep 17 00:00:00 2001
From: Jeffrey Wilcke <geffobscura@gmail.com>
Date: Sun, 30 Aug 2015 10:04:59 +0200
Subject: core, event/filter, xeth: refactored filter system

Moved the filtering system from `event` to `eth/filters` package and
removed the `core.Filter` object. The `filters.Filter` object now
requires a `common.Database` rather than a `eth.Backend` and invokes the
`core.GetBlockByX` directly rather than thru a "manager".
---
 eth/filters/filter_system.go | 133 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 eth/filters/filter_system.go

(limited to 'eth/filters/filter_system.go')

diff --git a/eth/filters/filter_system.go b/eth/filters/filter_system.go
new file mode 100644
index 000000000..9ad73a896
--- /dev/null
+++ b/eth/filters/filter_system.go
@@ -0,0 +1,133 @@
+// 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"
+
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/state"
+	"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 fires by the EVM (Ethereum Virtual Machine).
+type FilterSystem struct {
+	eventMux *event.TypeMux
+
+	filterMu sync.RWMutex
+	filterId int
+	filters  map[int]*Filter
+
+	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),
+	}
+	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.filterId++
+
+	return id
+}
+
+// Remove removes a filter by filter id
+func (fs *FilterSystem) Remove(id int) {
+	fs.filterMu.Lock()
+	defer fs.filterMu.Unlock()
+	if _, ok := fs.filters[id]; ok {
+		delete(fs.filters, 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
+	events := fs.eventMux.Subscribe(
+		//core.PendingBlockEvent{},
+		core.ChainEvent{},
+		core.TxPreEvent{},
+		state.Logs(nil))
+
+out:
+	for {
+		select {
+		case <-fs.quit:
+			break out
+		case event := <-events.Chan():
+			switch event := event.(type) {
+			case core.ChainEvent:
+				fs.filterMu.RLock()
+				for _, filter := range fs.filters {
+					if filter.BlockCallback != nil {
+						filter.BlockCallback(event.Block, event.Logs)
+					}
+				}
+				fs.filterMu.RUnlock()
+
+			case core.TxPreEvent:
+				fs.filterMu.RLock()
+				for _, filter := range fs.filters {
+					if filter.TransactionCallback != nil {
+						filter.TransactionCallback(event.Tx)
+					}
+				}
+				fs.filterMu.RUnlock()
+
+			case state.Logs:
+				fs.filterMu.RLock()
+				for _, filter := range fs.filters {
+					if filter.LogsCallback != nil {
+						msgs := filter.FilterLogs(event)
+						if len(msgs) > 0 {
+							filter.LogsCallback(msgs)
+						}
+					}
+				}
+				fs.filterMu.RUnlock()
+			}
+		}
+	}
+}
-- 
cgit