3eb94ec81b sync: Use decltype(auto) return type for WITH_LOCK (Carl Dong)
Pull request description:
> Now that we're using C++17, we can use the decltype(auto) return type
> for functions and lambda expressions.
>
> As demonstrated in this commit, this can simplify cases where previously
> the compiler failed to deduce the correct return type.
>
> Just for reference, for the "assign to ref" cases fixed here, there are
> 3 possible solutions:
>
> - Return a pointer and immediately deref as used before this commit
> - Make sure the function/lambda returns declspec(auto) as used after
> this commit
> - Class& i = WITH_LOCK(..., return std::ref(...));
>
> -----
>
> References:
> 1. https://en.cppreference.com/w/cpp/language/function#Return_type_deduction
> 2. https://en.cppreference.com/w/cpp/language/template_argument_deduction#Other_contexts
> 3. https://en.cppreference.com/w/cpp/language/auto
> 4. https://en.cppreference.com/w/cpp/language/decltype
>
> Explanations:
> 1. https://stackoverflow.com/a/21369192
> 2. https://stackoverflow.com/a/21369170
Thanks to sipa and ryanofsky for helping me understand this
ACKs for top commit:
jnewbery:
utACK 3eb94ec81b
hebasto:
ACK 3eb94ec81b, I have reviewed the code and it looks OK, I agree it can be merged. I have verified possible warnings:
ryanofsky:
Code review ACK 3eb94ec81b
Tree-SHA512: 5f55c7722aeca8ea70e5c1a8db93e93ba0e356e8967e7f607ada38003df4b153d73c29bd2cea8d7ec1344720d37d857ea7dbfd2a88da1d92e0e9cbb9abd287df
95975dd08d sync: detect double lock from the same thread (Vasil Dimov)
4df6567e4c sync: make EnterCritical() & push_lock() type safe (Vasil Dimov)
Pull request description:
Double lock of the same (non-recursive) mutex from the same thread would produce an undefined behavior. Detect this from `DEBUG_LOCKORDER` and react similarly to the deadlock detection.
This came up during discussion in another, related PR: https://github.com/bitcoin/bitcoin/pull/19238#discussion_r442394521.
ACKs for top commit:
laanwj:
code review ACK 95975dd08d
hebasto:
re-ACK 95975dd08d
Tree-SHA512: 375c62db7819e348bfaecc3bd82a7907fcd8f5af24f7d637ac82f3f16789da9fc127dbd0e37158a08e0dcbba01a55c6635caf1d8e9e827cf5a3747f7690a498e
The functions `EnterCritical()` and `push_lock()` take a pointer to a
mutex, but that pointer used to be of type `void*` because we use a few
different types for mutexes. This `void*` argument was not type safe
because somebody could have send a pointer to anything that is not a
mutex. Furthermore it wouldn't allow to check whether the passed mutex
is recursive or not.
Thus, change the functions to templated ones so that we can implement
stricter checks for non-recursive mutexes. This also simplifies the
callers of `EnterCritical()`.
FoundBlock class allows interfaces::Chain::findBlock to return more block
information without having lots of optional output parameters. FoundBlock class
is also used by other chain methods in upcoming commits.
There is mostly no change in behavior. Only exception is
CWallet::RescanFromTime now throwing NonFatalCheckError instead of
std::logic_error.
-BEGIN VERIFY SCRIPT-
# Delete outdated alias for RecursiveMutex
sed -i -e '/CCriticalSection/d' ./src/sync.h
# Replace use of outdated alias with RecursiveMutex
sed -i -e 's/CCriticalSection/RecursiveMutex/g' $(git grep -l CCriticalSection)
-END VERIFY SCRIPT-
Call sync.h primitives "locks" and "mutexes" instead of "blocks" and "waitable
critical sections" to match current coding conventions and c++11 standard
names.
This PR does not rename the "CCriticalSection" class (though this could be done
as a followup) because it is used everywhere and would swamp the other changes
in this PR. Plain mutexes should mostly be preferred instead of recursive
mutexes in new code anyway.
-BEGIN VERIFY SCRIPT-
set -x
set -e
ren() { git grep -l $1 | xargs sed -i s/$1/$2/; }
ren CCriticalBlock UniqueLock
ren CWaitableCriticalSection Mutex
ren CConditionVariable std::condition_variable
ren cs_GenesisWait g_genesis_wait_mutex
ren condvar_GenesisWait g_genesis_wait_cv
perl -0777 -pi -e 's/.*typedef.*condition_variable.*\n\n?//g' src/sync.h
-END VERIFY SCRIPT-
9c4dc597dd Use LOCK macros for non-recursive locks (Russell Yanofsky)
1382913e61 Make LOCK, LOCK2, TRY_LOCK work with CWaitableCriticalSection (Russell Yanofsky)
ba1f095aad MOVEONLY Move AnnotatedMixin declaration (Russell Yanofsky)
41b88e9337 Add unit test for DEBUG_LOCKORDER code (Russell Yanofsky)
Pull request description:
Make LOCK macros work with non-recursive mutexes, and use wherever possible for better deadlock detection.
Also add unit test for DEBUG_LOCKORDER code.
Tree-SHA512: 64ef209307f28ecd0813a283f15c6406138c6ffe7f6cbbd084161044db60e2c099a7d0d2edcd1c5e7770a115e9b931b486e86c9a777bdc96d2e8a9f4dc192942
They should also work with any other mutex type which std::unique_lock
supports.
There is no change in behavior for current code that calls these macros with
CCriticalSection mutexes.
89f0312 Remove redundant pwallet nullptr check (Matt Corallo)
c4784b5 Add a dev notes document describing the new wallet RPC blocking (Matt Corallo)
3ea8b75 Give ZMQ consistent order with UpdatedBlockTip on scheduler thread (Matt Corallo)
cb06edf Fix wallet RPC race by waiting for callbacks in sendrawtransaction (Matt Corallo)
e545ded Also call other wallet notify callbacks in scheduler thread (Matt Corallo)
17220d6 Use callbacks to cache whether wallet transactions are in mempool (Matt Corallo)
5d67a78 Add calls to CWallet::BlockUntilSyncedToCurrentChain() in RPCs (Matt Corallo)
5ee3172 Add CWallet::BlockUntilSyncedToCurrentChain() (Matt Corallo)
0b2f42d Add CallFunctionInQueue to wait on validation interface queue drain (Matt Corallo)
2b4b345 Add ability to assert a lock is not held in DEBUG_LOCKORDER (Matt Corallo)
0343676 Call TransactionRemovedFromMempool in the CScheduler thread (Matt Corallo)
a7d3936 Add a CValidationInterface::TransactionRemovedFromMempool (Matt Corallo)
Pull request description:
Based on #10179, this effectively reverts #9583, regaining most of the original speedups of #7946.
This concludes the work of #9725, #10178, and #10179.
See individual commit messages for more information.
Tree-SHA512: eead4809b0a75d1fb33b0765174ff52c972e45040635e38cf3686cef310859c1e6b3c00e7186cbd17374c6ae547bfbd6c1718fe36f26c76ba8a8b052d6ed7bc9
Commit 1.
This code was written by @TheBlueMatt in the following branch:
* https://github.com/TheBlueMatt/bitcoin/commits/2017-08-test-10923
This commit message was written by me (@practicalswift) who also squashed
@TheBlueMatt's commits into one and tried to summarize the changes made.
Commit 2.
Remove boost include. Remove boost mentions in comments.
6e8c48dc5 Add const to methods that do not modify the object for which it is called (practicalswift)
Pull request description:
Tree-SHA512: a6888111ba16fb796e320e60806e1a77d36f545989b5405dc7319992291800109eab0b8e8c286b784778f41f1ff5289e7cb6b4afd7aec77f385fbcafc02cffc1
Previously addnodes were in competition with outbound connections
for access to the eight outbound slots.
One result of this is that frequently a node with several addnode
configured peers would end up connected to none of them, because
while the addnode loop was in its two minute sleep the automatic
connection logic would fill any free slots with random peers.
This is particularly unwelcome to users trying to maintain links
to specific nodes for fast block relay or purposes.
Another result is that a group of nine or more nodes which are
have addnode configured towards each other can become partitioned
from the public network.
This commit introduces a new limit of eight connections just for
addnode peers which is not subject to any of the other connection
limitations (including maxconnections).
The choice of eight is sufficient so that under no condition would
a user find themselves connected to fewer addnoded peers than
previously. It is also low enough that users who are confused
about the significance of more connections and have gotten too
copy-and-paste happy will not consume more than twice the slot
usage of a typical user.
Any additional load on the network resulting from this will likely
be offset by a reduction in users applying even more wasteful
workaround for the prior behavior.
The retry delays are reduced to avoid nodes sitting around without
their added peers up, but are still sufficient to prevent overly
aggressive repeated connections. The reduced delays also make
the system much more responsive to the addnode RPC.
Ban-disconnects are also exempted for peers added via addnode since
the outbound addnode logic ignores bans. Previously it would ban
an addnode then immediately reconnect to it.
A minor change was also made to CSemaphoreGrant so that it is
possible to re-acquire via an object whos grant was moved.
The lockorder potential deadlock detection works by remembering for each
lock A that is acquired while holding another B the pair (A,B), and
triggering a warning when (B,A) already exists in the table.
A and B in the above text are represented by pointers to the CCriticalSection
object that is acquired. This does mean however that we need to clean up the
table entries that refer to any critical section which is destroyed, as it
memory address can potentially be used for another unrelated lock in the future.
Implement this clean up by remembering not only the pairs in forward direction,
but also backward direction. This allows for fast iteration over all pairs that
use a deleted CCriticalSection in either the first or the second position.
