Lower bound priority #7008

morcos · 2015-11-13T16:06:43Z

I think this is a good compromise with regards to priority for 0.12 release. It is a calculation of priority in which only inputs that are in the chain at the time the transaction enters the mempool are aged.

It is a minimal amount of code and changes the CTxMemPoolEntry::GetPriority function to return a lower bound of the correctly computed priority as opposed to an upper bound. This would allow the fast mining code in #6898 to use a priority calculation that at least ages the originally in chain inputs as opposed to using only starting priority.
I believe this better strikes the right balance between preserving the ability to meet previous policy objectives and adding too much complication to the code for a concept that is deprecated. I plan to close #6357 in favor of this.

One caveat: In the event of a reorg, if one of the originally in-chain inputs is now no longer in chain (or has been moved to a different height) the calculation will no longer be a strict lower bound on priority because it will not take this into account.

It should be kept in mind though, that this is a clear improvement on the current calculation.

(Built on top of #7007 so the tests pass)

(EDIT: For anyone that has already reviewed #6357, this is almost a strict subset)

sdaftuar · 2015-11-17T17:56:11Z

utACK

sipa · 2015-11-17T21:40:15Z

Concept ACK

morcos · 2015-11-17T21:46:05Z

This was rebased now that #7020 was merged, and I removed the concept of default arguments from the CTxMemPoolEntry constructor.

luke-jr · 2015-11-18T05:59:39Z

What are the benefits of this over #6357 ?

sipa · 2015-11-18T07:54:27Z

It's simpler.

Compute the value of inputs that already are in the chain at time of mempool entry and only increase priority due to aging for those inputs. This effectively changes the CTxMemPoolEntry's GetPriority calculation from an upper bound to a lower bound.

petertodd · 2015-11-20T20:50:54Z

src/coins.cpp

@@ -239,8 +240,9 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
        const CCoins* coins = AccessCoins(txin.prevout.hash);
        assert(coins);
        if (!coins->IsAvailable(txin.prevout.n)) continue;
-        if (coins->nHeight < nHeight) {
+        if (coins->nHeight <= nHeight) {


Why was this line changed?

Oh wait, I get it, never mind.

Good catch, but indeed :)

petertodd · 2015-11-20T21:17:47Z

utACK, modulo comment nit.

jtimon · 2015-11-23T12:59:17Z

utACK

dcousens · 2015-11-24T01:53:20Z

Is it worth changing this in light of the eventual removal of priority?
If it is, ACK.

sdaftuar · 2015-11-24T13:35:57Z

Added a commit to address @petertodd's comment nit.

@dcousens Yes I think this change is needed for 0.12, since all the priority code won't be eliminated yet. This seems like the best compromise for 0.12.

jtimon · 2015-11-24T14:41:33Z

In any case, merging this makes other mempool related PRs more readable, it's small and it doesn't preclude the future elimination of the priority code (and there's currently no rebased version of a priority-removing PR that I know of). So even if I'm very much in favor of directly removing the priority, I would be happy to see this merged soon.

I think some squashing could be done here though, at the very least for the comment fixup commit.

sipa · 2015-11-26T21:27:46Z

utACK

morcos · 2015-11-30T13:26:57Z

rebased

c035306 Change GetPriority calculation. (Alex Morcos) 71f1d9f Modify variable names for entry height and priority (Alex Morcos) 5945819 Remove default arguments for CTxMemPoolEntry() (Alex Morcos)

jtimon · 2015-12-02T13:47:00Z

src/txmempool.h

@@ -63,9 +63,10 @@ class CTxMemPoolEntry
    size_t nModSize; //! ... and modified size for priority
    size_t nUsageSize; //! ... and total memory usage
    int64_t nTime; //! Local time when entering the mempool
-    double dPriority; //! Priority when entering the mempool


What was the motivation to bike-sheed dPriority and nHeight?

This was originally the first part of the changes necessary for #6357 (now #7149)
It was necessary to distinguish between the two stored priorities and heights. The original "entry" priority and height and the latest calculated "cached" priority and the height that was calculated at.

It seemed logical to me to leave those changes in given that we didn't know whether the second half would be merged or not and given that they are more accurate names anyway.

It was necessary to distinguish between the two stored priorities and heights. The original "entry" priority and height and the latest calculated "cached" priority and the height that was calculated at.

I guess if the rename had been introduced when it was necessary instead of here I wouldn't have complained.

It seemed logical to me to leave those changes in given that we didn't know whether the second half would be merged or not and given that they are more accurate names anyway.

I'm confused, how are CTxMemPoolEntry::nHeight and CTxMemPoolEntry::dPriority "less accurate" than CTxMemPoolEntry::entryHeight and CTxMemPoolEntry::entryPriority ?

830eadf Solving rpc_fundrawtransaction.py amount rounding issue. (furszy) 6cf9778 ATMP: Do not try to get the inputs in zc tx. (furszy) 38efbb9 sync_blocks: Increase debugging to hunt down mempool_reorg intermittent failure (furszy) dd7855c sync_blocks: check that peer is connected when calling sync_*. (furszy) bc7d542 functional tests, sync_blocks only cleanup. (furszy) 1ae04e7 Fix mempool package tracking edge case (Suhas Daftuar) f4052aa Add test showing bug in mempool packages (furszy) 691749f rpc: Accept scientific notation for monetary amounts in JSON (furszy) b0f9051 Fix removeForReorg to use MedianTimePast (Suhas Daftuar) 92583c6 Don't call removeForReorg if DisconnectTip fails (Suhas Daftuar) bb77808 Track coinbase spends in CTxMemPoolEntry (furszy) f607f18 Change GetPriority calculation. (furszy) ac3c0f1 Remove default arguments for CTxMemPoolEntry() (furszy) 07eae9f Modify variable names for entry height and priority (furszy) 4356b31 Fix bug in mempool_tests unit test (Alex Morcos) f35ebe3 removeForReorg calls once-per-disconnect-> once-per-reorg (furszy) 7f5737f Fix comment in removeForReorg (furszy) 8ad82ca Fix removal of time-locked transactions during reorg (furszy) de74ab3 Move ProcessBlockFound reserveKey to optional. (furszy) Pull request description: More back ports and adaptations over the RPC values parsing and mempool. We need to get closer in this area :) . * bitcoin#6379 * bitcoin#6715 * bitcoin#6915 * bitcoin#7007 * bitcoin#7008 * bitcoin#12643 * bitcoin#18474 * bitcoin#18704 ACKs for top commit: Fuzzbawls: ACK 830eadf random-zebra: ACK 830eadf and merging... Tree-SHA512: 014b31008aaf09ebf838e21da59379a45565df440a77d66a0cd53e824a6d69673d6975d08243a43fb5a7ebd1a35c07d1d07412a87216b42e9d6f17a1c0bc5708

laanwj added the Mempool label Nov 13, 2015

morcos force-pushed the lowerBoundPriority branch from 0161cff to 5112684 Compare November 14, 2015 18:53

This was referenced Nov 14, 2015

Dynamic priority calculation #6357

Closed

Rename and comment priority calculation in TxMemPoolEntry #6292

Closed

Implement helper class for CTxMemPoolEntry constructor #7020

Merged

morcos force-pushed the lowerBoundPriority branch from 5112684 to bea369e Compare November 17, 2015 21:44

morcos mentioned this pull request Nov 18, 2015

Rewrite CreateNewBlock #6898

Merged

morcos added 3 commits November 19, 2015 21:28

Remove default arguments for CTxMemPoolEntry()

5945819

Modify variable names for entry height and priority

71f1d9f

Change GetPriority calculation.

c035306

Compute the value of inputs that already are in the chain at time of mempool entry and only increase priority due to aging for those inputs. This effectively changes the CTxMemPoolEntry's GetPriority calculation from an upper bound to a lower bound.

petertodd reviewed Nov 20, 2015
View reviewed changes

sipa added this to the 0.12.0 milestone Nov 28, 2015

morcos force-pushed the lowerBoundPriority branch 2 times, most recently from 40a0e82 to c035306 Compare November 30, 2015 13:18

laanwj merged commit c035306 into bitcoin:master Nov 30, 2015

jtimon reviewed Dec 2, 2015
View reviewed changes

sdaftuar mentioned this pull request Jan 15, 2016

0.12 release notes: Mining Policy Changes #7346

Merged

furszy mentioned this pull request Jun 25, 2020

RPC & Mempool back ports. PIVX-Project/PIVX#1707

Merged

bitcoin locked as resolved and limited conversation to collaborators Sep 8, 2021

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Lower bound priority #7008

Lower bound priority #7008

morcos commented Nov 13, 2015

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morcos commented Nov 17, 2015

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petertodd Nov 20, 2015

petertodd Nov 20, 2015

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petertodd commented Nov 20, 2015

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dcousens commented Nov 24, 2015

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sipa commented Nov 26, 2015

morcos commented Nov 30, 2015

jtimon Dec 2, 2015

morcos Dec 2, 2015

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Lower bound priority #7008

Lower bound priority #7008

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morcos commented Nov 13, 2015

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