This implements orphan expiration in the mempool such that any orphans
that have not had their ancestors materialize within 15 minutes of their
initial arrival time will be evicted which in turn will remove any other
orphans that attempted to redeem it.
In order to perform the evictions with reasonable efficiency, an
opportunistic scan interval of 5 minutes is used. That is to say that
there is not a hard deadline on the scan interval and instead it runs
when a new orphan is added to the pool if enough time has passed.
The following is an example of running this code against the main
network for around 30 minutes:
23:05:34 2016-10-24 [DBG] TXMP: Expired 3 orphans (remaining: 254)
23:10:38 2016-10-24 [DBG] TXMP: Expired 112 orphans (remaining: 231)
23:15:43 2016-10-24 [DBG] TXMP: Expired 95 orphans (remaining: 206)
23:20:44 2016-10-24 [DBG] TXMP: Expired 90 orphans (remaining: 191)
23:25:51 2016-10-24 [DBG] TXMP: Expired 71 orphans (remaining: 191)
23:30:55 2016-10-24 [DBG] TXMP: Expired 70 orphans (remaining: 105)
23:36:19 2016-10-24 [DBG] TXMP: Expired 55 orphans (remaining: 107)
As can be seen from the above, without orphan expiration on this data
set, the orphan pool would have grown an additional 496 entries.
This does the minimum work necessary to refactor the mempool code into
its own package. The idea is that separating this code into its own
package will greatly improve its testability, allow independent
benchmarking and profiling, and open up some interesting opportunities
for future development related to the memory pool.
There are likely some areas related to policy that could be further
refactored, however it is better to do that in future commits in order
to keep the changeset as small as possible during this refactor.
Overview of the major changes:
- Create the new package
- Move several files into the new package:
- mempool.go -> mempool/mempool.go
- mempoolerror.go -> mempool/error.go
- policy.go -> mempool/policy.go
- policy_test.go -> mempool/policy_test.go
- Update mempool logging to use the new mempool package logger
- Rename mempoolPolicy to Policy (so it's now mempool.Policy)
- Rename mempoolConfig to Config (so it's now mempool.Config)
- Rename mempoolTxDesc to TxDesc (so it's now mempool.TxDesc)
- Rename txMemPool to TxPool (so it's now mempool.TxPool)
- Move defaultBlockPrioritySize to the new package and export it
- Export DefaultMinRelayTxFee from the mempool package
- Export the CalcPriority function from the mempool package
- Introduce a new RawMempoolVerbose function on the TxPool and update
the RPC server to use it
- Update all references to the mempool to use the package.
- Add a skeleton README.md
