RPC: savemempool: Don’t write mempool.dat while not having the previous one in memory #12142

1. 
   jtimon commented at 0:57 am on January 11, 2018: contributor

   Currently it is possible to stupidly lose mempool data by calling the rpc “savemempool” before the previous stored mempool has been read and processed to the memory mempool.

   I haven’t looked at the code yet, but at minimum one ugly solution would be to have a global g_is_mempool_read_finished (or something of the short) that starts false and gets sets to true once the reading is reading processing of mempool.dat is successfully finished. The rpc savemempool checks this global on the start and returns a an error while it remains false.

2. jtimon referenced this in commit cce6c03e19 on Jan 11, 2018
3. 
   sipa commented at 7:29 am on January 11, 2018: member

   Good point, seems easy to fix.
4. fanquake added the label RPC/REST/ZMQ on Jan 11, 2018
5. fanquake added the label Mempool on Jan 11, 2018
6. 
   jtimon commented at 9:01 pm on January 12, 2018: contributor

   Created https://github.com/bitcoin/bitcoin/pull/12172
7. 
   Willtech commented at 0:51 am on January 14, 2018: contributor

   Having a global g_is_mempool_read_finished (or something of the short) may be one ugly solution but, it is also useful for (proposed/intended) other purposes.

   I haven’t looked at your fix but presume that also the mempool is not again saved if exiting before the mempool is finished loading when persistmempool is true. Is that the expected behaviour? Ideally, it should add any newly received transactions to the dump in that case. Probably outside the scope of your fix.

   It should be noted that on my not particularly low spec system running Fedora, loading mempool takes over 1 hour when the node is started so, it is a long process on some systems, it is possible to receive lots of new transactions if the node is restarted again in that time.

8. jtimon referenced this in commit 198eee0190 on Jan 20, 2018
9. laanwj closed this on Mar 29, 2018

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Contributors
jtimon sipa Willtech

Labels
RPC/REST/ZMQ Mempool