wehub-resource-sync
119 lines
3.2 KiB
Go
119 lines
3.2 KiB
Go
// Copyright 2024 Dolthub, 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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package pull
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import (
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"context"
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"errors"
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"io"
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"sync"
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"github.com/dolthub/dolt/go/store/hash"
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"github.com/dolthub/dolt/go/store/nbs"
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)
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type GetManyer interface {
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GetManyCompressed(ctx context.Context, hashes hash.HashSet, found func(context.Context, nbs.ToChunker)) error
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}
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type ChunkFetcherable interface {
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ChunkFetcher(ctx context.Context, recorder nbs.StatsRecorder) nbs.ChunkFetcher
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}
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// GetChunkFetcher returns a ChunkFetcher for |cs|. If |cs| is capable of
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// producing its own fetcher (e.g. a remote chunk store with range coalescing
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// and concurrent downloads), |recorder|, if non-nil, is threaded into it to
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// receive per-download statistics. The fallback PullChunkFetcher does no
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// ranged downloads, so |recorder| is unused in that case.
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func GetChunkFetcher(ctx context.Context, cs GetManyer, recorder nbs.StatsRecorder) nbs.ChunkFetcher {
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if fable, ok := cs.(ChunkFetcherable); ok {
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return fable.ChunkFetcher(ctx, recorder)
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}
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return NewPullChunkFetcher(cs)
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}
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// A PullChunkFetcher is a simple implementation of |ChunkFetcher| based on
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// calling GetManyCompressed.
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//
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// It only has one outstanding GetManyCompressed call at a time.
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type PullChunkFetcher struct {
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getter GetManyer
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resCh chan nbs.ToChunker
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closedCh chan struct{}
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}
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func NewPullChunkFetcher(getter GetManyer) *PullChunkFetcher {
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ret := &PullChunkFetcher{
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getter: getter,
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resCh: make(chan nbs.ToChunker),
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closedCh: make(chan struct{}),
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}
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return ret
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}
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func (f *PullChunkFetcher) Get(ctx context.Context, hashes hash.HashSet) error {
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var mu sync.Mutex
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missing := hashes.Copy()
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// Blocking get, no concurrency, only one fetcher.
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err := f.getter.GetManyCompressed(ctx, hashes, func(ctx context.Context, chk nbs.ToChunker) {
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mu.Lock()
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missing.Remove(chk.Hash())
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mu.Unlock()
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select {
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case <-ctx.Done():
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case f.resCh <- chk:
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}
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})
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if err != nil {
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return err
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}
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for h := range missing {
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select {
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case <-ctx.Done():
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return context.Cause(ctx)
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case f.resCh <- nbs.CompressedChunk{H: h}:
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case <-f.closedCh:
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return errors.New("PullChunkFetcher: Get on closed Fetcher.")
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}
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}
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return nil
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}
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func (f *PullChunkFetcher) CloseSend() error {
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close(f.resCh)
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return nil
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}
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func (f *PullChunkFetcher) Close() error {
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close(f.closedCh)
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return nil
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}
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func (f *PullChunkFetcher) Recv(ctx context.Context) (nbs.ToChunker, error) {
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select {
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case res, ok := <-f.resCh:
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if !ok {
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return nbs.CompressedChunk{}, io.EOF
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}
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return res, nil
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case <-ctx.Done():
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return nbs.CompressedChunk{}, context.Cause(ctx)
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case <-f.closedCh:
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return nbs.CompressedChunk{}, errors.New("PullChunkFetcher: Recv on closed Fetcher.")
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}
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}
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