Merge pull request #1850 from harshavardhana/list-rewrite
XL: Implement ListObjects channel and pool management.master
Harshavardhana
9 years ago
commit
73ddb5be75
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/* |
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* Minio Cloud Storage, (C) 2016 Minio, Inc. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package main |
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import ( |
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"errors" |
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"sync" |
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"time" |
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) |
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// Global lookup timeout.
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const ( |
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globalLookupTimeout = time.Minute * 30 // 30minutes.
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) |
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// errWalkAbort - returned by the treeWalker routine, it signals the end of treeWalk.
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var errWalkAbort = errors.New("treeWalk abort") |
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// treeWalkerPoolInfo - tree walker pool info carries temporary walker
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// channel stored until timeout is called.
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type treeWalkerPoolInfo struct { |
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treeWalkerCh chan treeWalker |
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treeWalkerDoneCh chan struct{} |
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doneCh chan<- struct{} |
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} |
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// treeWalkerPool - tree walker pool is a set of temporary tree walker
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// objects. Any item stored in the pool will be removed automatically at
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// a given timeOut value. This pool is safe for use by multiple
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// goroutines simultaneously. pool's purpose is to cache tree walker
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// channels for later reuse.
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type treeWalkerPool struct { |
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pool map[listParams][]treeWalkerPoolInfo |
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timeOut time.Duration |
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lock *sync.Mutex |
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} |
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// newTreeWalkerPool - initialize new tree walker pool.
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func newTreeWalkerPool(timeout time.Duration) *treeWalkerPool { |
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tPool := &treeWalkerPool{ |
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pool: make(map[listParams][]treeWalkerPoolInfo), |
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timeOut: timeout, |
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lock: &sync.Mutex{}, |
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} |
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return tPool |
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} |
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// Release - selects an item from the pool based on the input
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// listParams, removes it from the pool, and returns treeWalker
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// channels. Release will return nil, if listParams is not
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// recognized.
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func (t treeWalkerPool) Release(params listParams) (treeWalkerCh chan treeWalker, treeWalkerDoneCh chan struct{}) { |
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t.lock.Lock() |
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defer t.lock.Unlock() |
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walks, ok := t.pool[params] // Pick the valid walks.
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if ok { |
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if len(walks) > 0 { |
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// Pop out the first valid walk entry.
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walk := walks[0] |
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walks = walks[1:] |
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if len(walks) > 0 { |
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t.pool[params] = walks |
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} else { |
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delete(t.pool, params) |
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} |
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walk.doneCh <- struct{}{} |
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return walk.treeWalkerCh, walk.treeWalkerDoneCh |
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} |
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} |
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// Release return nil if params not found.
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return nil, nil |
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} |
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// Set - adds new list params along with treeWalker channel to the
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// pool for future. Additionally this also starts a go routine which
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// waits at the configured timeout. Additionally this go-routine is
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// also closed pro-actively by 'Release' call when the treeWalker
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// item is obtained from the pool.
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func (t treeWalkerPool) Set(params listParams, treeWalkerCh chan treeWalker, treeWalkerDoneCh chan struct{}) { |
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t.lock.Lock() |
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defer t.lock.Unlock() |
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// Should be a buffered channel so that Release() never blocks.
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var doneCh = make(chan struct{}, 1) |
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walkInfo := treeWalkerPoolInfo{ |
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treeWalkerCh: treeWalkerCh, |
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treeWalkerDoneCh: treeWalkerDoneCh, |
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doneCh: doneCh, |
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} |
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// Append new walk info.
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t.pool[params] = append(t.pool[params], walkInfo) |
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// Safe expiry of treeWalkerCh after timeout.
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go func(doneCh <-chan struct{}) { |
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select { |
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// Wait until timeOut
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case <-time.After(t.timeOut): |
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t.lock.Lock() |
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walks, ok := t.pool[params] // Look for valid walks.
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if ok { |
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// Look for walkInfo, remove it from the walks list.
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for i, walk := range walks { |
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if walk == walkInfo { |
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walks = append(walks[:i], walks[i+1:]...) |
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} |
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} |
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// Walks is empty we have no more pending requests.
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// Remove map entry.
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if len(walks) == 0 { |
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delete(t.pool, params) |
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} else { // Save the updated walks.
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t.pool[params] = walks |
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} |
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} |
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// Close tree walker for the backing go-routine to die.
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close(treeWalkerDoneCh) |
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t.lock.Unlock() |
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case <-doneCh: |
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return |
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} |
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}(doneCh) |
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} |
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