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// Copyright 2015 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/>.
// Contains the external API side message filter for watching, pooling and polling
// matched whisper messages, also serializing data access to avoid duplications.
package xeth
import (
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
)
// whisperFilter is the message cache matching a specific filter, accumulating
// inbound messages until the are requested by the client.
type whisperFilter struct {
id int // Filter identifier for old message retrieval
ref *Whisper // Whisper reference for old message retrieval
cache []WhisperMessage // Cache of messages not yet polled
skip map[common.Hash]struct{} // List of retrieved messages to avoid duplication
update time.Time // Time of the last message query
lock sync.RWMutex // Lock protecting the filter internals
}
// newWhisperFilter creates a new serialized, poll based whisper topic filter.
func newWhisperFilter(id int, ref *Whisper) *whisperFilter {
return &whisperFilter{
id: id,
ref: ref,
update: time.Now(),
skip: make(map[common.Hash]struct{}),
}
}
// messages retrieves all the cached messages from the entire pool matching the
// filter, resetting the filter's change buffer.
func (w *whisperFilter) messages() []WhisperMessage {
w.lock.Lock()
defer w.lock.Unlock()
w.cache = nil
w.update = time.Now()
w.skip = make(map[common.Hash]struct{})
messages := w.ref.Messages(w.id)
for _, message := range messages {
w.skip[message.ref.Hash] = struct{}{}
}
return messages
}
// insert injects a new batch of messages into the filter cache.
func (w *whisperFilter) insert(messages ...WhisperMessage) {
w.lock.Lock()
defer w.lock.Unlock()
for _, message := range messages {
if _, ok := w.skip[message.ref.Hash]; !ok {
w.cache = append(w.cache, messages...)
}
}
}
// retrieve fetches all the cached messages from the filter.
func (w *whisperFilter) retrieve() (messages []WhisperMessage) {
w.lock.Lock()
defer w.lock.Unlock()
messages, w.cache = w.cache, nil
w.update = time.Now()
return
}
// activity returns the last time instance when client requests were executed on
// the filter.
func (w *whisperFilter) activity() time.Time {
w.lock.RLock()
defer w.lock.RUnlock()
return w.update
}
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