forked from Silverfish/proton-bridge
88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
// Copyright (c) 2024 Proton AG
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//
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// This file is part of Proton Mail Bridge.
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//
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// Proton Mail Bridge is free software: you can redistribute it and/or modify
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// it under the terms of the GNU 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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// Proton Mail Bridge 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 General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
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package imapservice
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import (
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"context"
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"errors"
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"sync"
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"github.com/ProtonMail/gluon/connector"
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)
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type CacheAccessor interface {
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connector.IMAPState
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Close()
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}
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// SharedCache is meant to protect access to the database and guarantee it's always valid. There may be some corner
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// cases where the Gluon connector can get closed while we are processing events in parallel. If for some reason
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// Gluon closes the database, the instance is invalidated and any attempts to access this state will return
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// `ErrCacheNotAvailable`.
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type SharedCache struct {
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cache connector.IMAPState
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lock sync.RWMutex
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}
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func NewSharedCached() *SharedCache {
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return &SharedCache{}
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}
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var ErrCacheNotAvailable = errors.New("cache no longer available")
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func (s *SharedCache) Set(cache connector.IMAPState) {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.cache = cache
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}
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func (s *SharedCache) Close() {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.cache = nil
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}
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func (s *SharedCache) Acquire() (CacheAccessor, error) {
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s.lock.RLock()
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if s.cache == nil {
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s.lock.RUnlock()
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return nil, ErrCacheNotAvailable
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}
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return &cacheAccessor{sharedCache: s}, nil
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}
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type cacheAccessor struct {
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sharedCache *SharedCache
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}
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func (c cacheAccessor) Read(ctx context.Context, f func(context.Context, connector.IMAPStateRead) error) error {
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return c.sharedCache.cache.Read(ctx, f)
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}
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func (c cacheAccessor) Write(ctx context.Context, f func(context.Context, connector.IMAPStateWrite) error) error {
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return c.sharedCache.cache.Write(ctx, f)
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}
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func (c cacheAccessor) Close() {
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c.sharedCache.lock.RUnlock()
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}
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