74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
// package offline implements an object that implements the exchange
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// interface but returns nil values to every request.
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package offline
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import (
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"context"
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blocks "github.com/ipfs/go-block-format"
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cid "github.com/ipfs/go-cid"
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blockstore "github.com/ipfs/go-ipfs-blockstore"
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exchange "github.com/ipfs/go-ipfs-exchange-interface"
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)
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func Exchange(bs blockstore.Blockstore) exchange.Interface {
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return &offlineExchange{bs: bs}
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}
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// offlineExchange implements the Exchange interface but doesn't return blocks.
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// For use in offline mode.
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type offlineExchange struct {
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bs blockstore.Blockstore
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}
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// GetBlock returns nil to signal that a block could not be retrieved for the
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// given key.
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// NB: This function may return before the timeout expires.
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func (e *offlineExchange) GetBlock(_ context.Context, k cid.Cid) (blocks.Block, error) {
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return e.bs.Get(k)
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}
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// HasBlock always returns nil.
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func (e *offlineExchange) HasBlock(b blocks.Block) error {
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return e.bs.Put(b)
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}
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// Close always returns nil.
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func (_ *offlineExchange) Close() error {
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// NB: exchange doesn't own the blockstore's underlying datastore, so it is
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// not responsible for closing it.
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return nil
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}
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func (e *offlineExchange) GetBlocks(ctx context.Context, ks []cid.Cid) (<-chan blocks.Block, error) {
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out := make(chan blocks.Block)
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go func() {
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defer close(out)
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var misses []cid.Cid
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for _, k := range ks {
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hit, err := e.bs.Get(k)
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if err != nil {
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misses = append(misses, k)
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// a long line of misses should abort when context is cancelled.
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select {
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// TODO case send misses down channel
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case <-ctx.Done():
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return
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default:
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continue
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}
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}
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select {
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case out <- hit:
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case <-ctx.Done():
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return
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}
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}
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}()
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return out, nil
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}
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func (e *offlineExchange) IsOnline() bool {
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return false
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}
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