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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/tracing.md | 32 |
1 files changed, 22 insertions, 10 deletions
diff --git a/doc/tracing.md b/doc/tracing.md index 68de376043..6ec6a6c218 100644 --- a/doc/tracing.md +++ b/doc/tracing.md @@ -110,22 +110,31 @@ Arguments passed: ### Context `utxocache` +The following tracepoints cover the in-memory UTXO cache. UTXOs are, for example, +added to and removed (spent) from the cache when we connect a new block. +**Note**: Bitcoin Core uses temporary clones of the _main_ UTXO cache +(`chainstate.CoinsTip()`). For example, the RPCs `generateblock` and +`getblocktemplate` call `TestBlockValidity()`, which applies the UTXO set +changes to a temporary cache. Similarly, mempool consistency checks, which are +frequent on regtest, also apply the the UTXO set changes to a temporary cache. +Changes to the _main_ UTXO cache and to temporary caches trigger the tracepoints. +We can't tell if a temporary cache or the _main_ cache was changed. + #### Tracepoint `utxocache:flush` -Is called *after* the caches are flushed depending on the mode -`CChainState::FlushStateToDisk` is called with. +Is called *after* the in-memory UTXO cache is flushed. Arguments passed: -1. Duration in microseconds as `int64` +1. Time it took to flush the cache microseconds as `int64` 2. Flush state mode as `uint32`. It's an enumerator class with values `0` (`NONE`), `1` (`IF_NEEDED`), `2` (`PERIODIC`), `3` (`ALWAYS`) -3. Number of coins flushed as `uint64` -4. Memory usage in bytes as `uint64` -5. If the flush was pruned as `bool` +3. Cache size (number of coins) before the flush as `uint64` +4. Cache memory usage in bytes as `uint64` +5. If pruning caused the flush as `bool` #### Tracepoint `utxocache:add` -It is called when a new coin is added to the UTXO cache. +Is called when a coin is added to a UTXO cache. This can be a temporary UTXO cache too. Arguments passed: 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) @@ -136,7 +145,7 @@ Arguments passed: #### Tracepoint `utxocache:spent` -It is called when a coin is spent from the UTXO cache. +Is called when a coin is spent from a UTXO cache. This can be a temporary UTXO cache too. Arguments passed: 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) @@ -147,14 +156,17 @@ Arguments passed: #### Tracepoint `utxocache:uncache` -It is called when the UTXO with the given outpoint is removed from the cache. +Is called when a coin is purposefully unloaded from a UTXO cache. This +happens, for example, when we load an UTXO into a cache when trying to accept +a transaction that turns out to be invalid. The loaded UTXO is uncached to avoid +filling our UTXO cache up with irrelevant UTXOs. Arguments passed: 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) 2. Output index as `uint32` 3. Block height the coin was uncached, as `uint32` 4. Value of the coin as `int64` -. If the coin is a coinbase as `bool` +5. If the coin is a coinbase as `bool` ## Adding tracepoints to Bitcoin Core |