Expose the SubscribeHeadersSingle function
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tomaszslabon
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The `SubscribeHeadersSingle` function subscribes to receive the header of the current blockchain tip. Unlike `SubscribeHeaders`, this function only returns the tip and does not listen for new block headers. Worth noting that this action still creates a new subscription in the Electrum server. The protocol does neither support a single-shot request for the current blockchain tip nor subscription cancellation. Although this limitation causes a slight resource overhead on the client, it does not cause a memory leak like the `SubscribeHeaders` method which spawns a goroutine that may hang on the channel if the caller is no longer pulling from it.
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tomaszslabon
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Feb 6, 2024
lukasz-zimnoch
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This is done in order to pull changes introduced in keep-network/go-electrum#5
lukasz-zimnoch
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So far, `GetLatestBlockHeight` function used `SubscribeHeaders` under the hood. That caused a memory leak because `GetLatestBlockHeight` was not interested in reading from the returned `headersChan` channel. Each call to `GetLatestBlockHeight` produced a new dangling goroutine blocked on a buffered channel holding one item Here we replace `SubscribeHeaders` with `SubscribeHeadersSingle` which does not create a goroutine supposed to handle future headers notifications. The `SubscribeHeadersSingle` just return the current chain tip and ignores further notifications coming from the Electrum server. See keep-network/go-electrum#5 for further reference.
This was referenced Feb 7, 2024
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Closes: #3739 Depends on: keep-network/go-electrum#5 Depends on: #3774 So far, the `GetLatestBlockHeight` function of the Electrum client was using `go-electrum`'s `SubscribeHeaders` under the hood. That caused a memory leak because `GetLatestBlockHeight` was not interested in reading from the returned `headersChan` channel. Each call to `GetLatestBlockHeight` produced a new dangling goroutine blocked on a buffered channel with one item inside. Here we replace `SubscribeHeaders` with `SubscribeHeadersSingle` which does not create a goroutine supposed to handle future headers notifications. The `SubscribeHeadersSingle` just returns the current chain tip and ignores further notifications coming from the Electrum server. See keep-network/go-electrum#5 for further reference.
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This is done in order to pull changes introduced in keep-network/go-electrum#5 (cherry picked from commit b3b800c)
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So far, `GetLatestBlockHeight` function used `SubscribeHeaders` under the hood. That caused a memory leak because `GetLatestBlockHeight` was not interested in reading from the returned `headersChan` channel. Each call to `GetLatestBlockHeight` produced a new dangling goroutine blocked on a buffered channel holding one item Here we replace `SubscribeHeaders` with `SubscribeHeadersSingle` which does not create a goroutine supposed to handle future headers notifications. The `SubscribeHeadersSingle` just return the current chain tip and ignores further notifications coming from the Electrum server. See keep-network/go-electrum#5 for further reference. (cherry picked from commit fb91c33)
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Refs: keep-network/keep-core#3739
The
SubscribeHeadersSinglefunction subscribes to receive the header of the current blockchain tip. UnlikeSubscribeHeaders, this function only returns the tip and does not listen for new block headers.Worth noting that this action still creates a new subscription in the Electrum server. The protocol does neither support a single-shot request for the current blockchain tip nor subscription cancellation. Although this limitation causes a slight resource overhead on the client, it does not cause a memory leak like the
SubscribeHeadersmethod which spawns a goroutine that may hang on the channel if the caller is no longer pulling from it.