Several fixes/improvements related to distributed traces.
Remove "key" attributes and the TRACING_SPAN_ATTRIBUTES_ENABLED knob: we almost never want to log actual keys (as they can contain private data), however, we do want to use other span attributes.
In Transaction::setTransactionID, properly propagate spanContext flags, and set all copies of spancontext
Previously we did not null out "attributes" in `Span& Span::operator=(Span&& o);`, but we destroyed the arena owning memory referenced by "attributes". Fix that by nulling out "attributes", and rewrite it in a way that's (hopefully) less error-prone.
ASAN diagnostic:
```
==24==WARNING: ASan doesn't fully support makecontext/swapcontext functions and may produce false positives in some cases!
=================================================================
==24==ERROR: AddressSanitizer: heap-use-after-free on address 0x60300033fa06 at pc 0x0000026eadcf bp 0x7ffca646fe50 sp 0x7ffca646f618
READ of size 9 at 0x60300033fa06 thread T0
#0 0x26eadce in __asan_memmove /tmp/llvm-project/compiler-rt/lib/asan/asan_interceptors_memintrinsics.cpp:30:3
#1 0xd43db76 in __copy<const unsigned char, unsigned char> /usr/local/bin/../include/c++/v1/__algorithm/copy.h:59:9
#2 0xd43db76 in copy<const unsigned char *, unsigned char *> /usr/local/bin/../include/c++/v1/__algorithm/copy.h:72:13
#3 0xd43db76 in write_bytes /mnt/ephemeral/anoyes/foundationdb/fdbrpc/include/fdbrpc/Msgpack.h:45:3
#4 0xd43db76 in serialize_string(unsigned char const*, int, MsgpackBuffer&) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/include/fdbrpc/Msgpack.h:109:6
#5 0xd43d208 in void serialize_map<SmallVectorRef<KeyValueRef, 1> >(SmallVectorRef<KeyValueRef, 1> const&, MsgpackBuffer&) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/include/fdbrpc/Msgpack.h:154:3
#6 0xd42e2a2 in (anonymous namespace)::UDPTracer::serialize_span(Span const&, MsgpackBuffer&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/Tracing.actor.cpp:157:3
#7 0xd42c8f4 in (anonymous namespace)::FastUDPTracer::trace(Span const&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/Tracing.actor.cpp:301:3
#8 0xd41dfe2 in Span::operator=(Span&&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/Tracing.actor.cpp:355:13
#9 0xc3eb122 in (anonymous namespace)::ReadVersionBatcherActorState<(anonymous namespace)::ReadVersionBatcherActor>::a_body1loopBody1cont1(int) /mnt/ephemeral/anoyes/foundationdb/fdbclient/NativeAPI.actor.cpp:7180:9
#10 0xc3e386d in a_body1loopBody1when2 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbclient/NativeAPI.actor.g.cpp:32322:15
#11 0xc3e386d in a_callback_fire /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbclient/NativeAPI.actor.g.cpp:32434:4
#12 0xc3e386d in ActorCallback<(anonymous namespace)::ReadVersionBatcherActor, 1, Void>::fire(Void const&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:1316:34
#13 0x278af3f in void SAV<Void>::send<Void>(Void&&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:655:23
#14 0xdd2dc36 in send<Void> /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:901:8
#15 0xdd2dc36 in Sim2::execTask(Sim2::PromiseTask&) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/sim2.actor.cpp:2319:15
#16 0xdd2cf0e in Sim2::runLoop(Sim2*) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/sim2.actor.cpp:1279:11
#17 0x7ebdf2e in main /mnt/ephemeral/anoyes/foundationdb/fdbserver/fdbserver.actor.cpp:2276:17
#18 0x7f62c7be6554 in __libc_start_main (/lib64/libc.so.6+0x22554)
#19 0x266f028 in _start (/mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/bin/fdbserver+0x266f028)
0x60300033fa06 is located 6 bytes inside of 32-byte region [0x60300033fa00,0x60300033fa20)
freed by thread T0 here:
#0 0x26eb352 in free /tmp/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:111:3
#1 0xdd90118 in ArenaBlock::destroy() /mnt/ephemeral/anoyes/foundationdb/flow/Arena.cpp:466:6
#2 0xdd8f0b0 in delref /mnt/ephemeral/anoyes/foundationdb/flow/Arena.cpp:173:3
#3 0xdd8f0b0 in delref<ArenaBlock> /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/FastRef.h:95:7
#4 0xdd8f0b0 in operator= /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/FastRef.h:147:5
#5 0xdd8f0b0 in Arena::operator=(Arena&&) /mnt/ephemeral/anoyes/foundationdb/flow/Arena.cpp:119:36
#6 0xd41dfed in Span::operator=(Span&&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/Tracing.actor.cpp:357:8
#7 0xc3eb122 in (anonymous namespace)::ReadVersionBatcherActorState<(anonymous namespace)::ReadVersionBatcherActor>::a_body1loopBody1cont1(int) /mnt/ephemeral/anoyes/foundationdb/fdbclient/NativeAPI.actor.cpp:7180:9
#8 0xc3e386d in a_body1loopBody1when2 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbclient/NativeAPI.actor.g.cpp:32322:15
#9 0xc3e386d in a_callback_fire /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbclient/NativeAPI.actor.g.cpp:32434:4
#10 0xc3e386d in ActorCallback<(anonymous namespace)::ReadVersionBatcherActor, 1, Void>::fire(Void const&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:1316:34
#11 0x278af3f in void SAV<Void>::send<Void>(Void&&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:655:23
#12 0xdd2dc36 in send<Void> /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:901:8
#13 0xdd2dc36 in Sim2::execTask(Sim2::PromiseTask&) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/sim2.actor.cpp:2319:15
#14 0xdd2cf0e in Sim2::runLoop(Sim2*) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/sim2.actor.cpp:1279:11
#15 0x7ebdf2e in main /mnt/ephemeral/anoyes/foundationdb/fdbserver/fdbserver.actor.cpp:2276:17
#16 0x7f62c7be6554 in __libc_start_main (/lib64/libc.so.6+0x22554)
previously allocated by thread T0 here:
#0 0x26ebeb2 in aligned_alloc /tmp/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:176:3
#1 0xdd8e5e0 in ArenaBlock::create(int, Reference<ArenaBlock>&) /mnt/ephemeral/anoyes/foundationdb/flow/Arena.cpp:339:21
#2 0xdd91139 in ArenaBlock::allocate(Reference<ArenaBlock>&, int) /mnt/ephemeral/anoyes/foundationdb/flow/Arena.cpp:322:7
#3 0x2bbf49b in operator new[] /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/Arena.h:206:9
#4 0x2bbf49b in StringRef /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/Arena.h:446:54
#5 0x2bbf49b in Span::Span(SpanContext const&, Location const&, SpanContext const&, std::initializer_list<SpanContext> const&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/include/fdbclient/Tracing.h:141:33
#6 0x2bbef25 in Span::Span(Location const&, SpanContext const&, std::initializer_list<SpanContext> const&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/include/fdbclient/Tracing.h:148:6
#7 0xc1bd941 in Span /mnt/ephemeral/anoyes/foundationdb/fdbclient/include/fdbclient/Tracing.h:160:44
#8 0xc1bd941 in ReadVersionBatcherActorState /mnt/ephemeral/anoyes/foundationdb/fdbclient/NativeAPI.actor.cpp:7125:6
#9 0xc1bd941 in ReadVersionBatcherActor /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbclient/NativeAPI.actor.g.cpp:32621:6
#10 0xc1bd941 in readVersionBatcher(DatabaseContext* const&, FutureStream<DatabaseContext::VersionRequest> const&, TransactionPriority const&, unsigned int const&) /mnt/ephemeral/anoyes/foundationdb/fdbclient/NativeAPI.actor.cpp:7098:26
#11 0xc1b316a in Transaction::getReadVersion(unsigned int) /mnt/ephemeral/anoyes/foundationdb/fdbclient/NativeAPI.actor.cpp:7366:8
#12 0xc19055f in getReadVersion /mnt/ephemeral/anoyes/foundationdb/fdbclient/include/fdbclient/NativeAPI.actor.h:315:44
#13 0xc19055f in Transaction::get(Standalone<StringRef> const&, Snapshot) /mnt/ephemeral/anoyes/foundationdb/fdbclient/NativeAPI.actor.cpp:5314:13
#14 0x5eca2f1 in a_body1 /mnt/ephemeral/anoyes/foundationdb/fdbserver/MoveKeys.actor.cpp:190:55
#15 0x5eca2f1 in ReadMoveKeysLockActor /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/MoveKeys.actor.g.cpp:1001:9
#16 0x5eca2f1 in readMoveKeysLock(Transaction* const&, MoveKeysLock* const&) /mnt/ephemeral/anoyes/foundationdb/fdbserver/MoveKeys.actor.cpp:188:26
#17 0x5ee590d in a_body1loopBody1 /mnt/ephemeral/anoyes/foundationdb/fdbserver/MoveKeys.actor.cpp:228:39
#18 0x5ee590d in (anonymous namespace)::TakeMoveKeysLockActorState<(anonymous namespace)::TakeMoveKeysLockActor>::a_body1loopHead1(int) /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/MoveKeys.actor.g.cpp:1421:49
#19 0x5ecb801 in a_body1 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/MoveKeys.actor.g.cpp:1400:16
#20 0x5ecb801 in TakeMoveKeysLockActor /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/MoveKeys.actor.g.cpp:1807:9
#21 0x5ecb801 in takeMoveKeysLock(Database const&, UID const&) /mnt/ephemeral/anoyes/foundationdb/fdbserver/MoveKeys.actor.cpp:216:34
#22 0x542a421 in DDTxnProcessor::takeMoveKeysLock(UID const&) const /mnt/ephemeral/anoyes/foundationdb/fdbserver/DDTxnProcessor.actor.cpp:620:9
#23 0x562aa75 in takeMoveKeysLock /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:330:69
#24 0x562aa75 in DataDistributor::InitActorState<DataDistributor::InitActor>::a_body1loopBody1(int) /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:370:44
#25 0x562a0ba in a_body1loopHead1 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:1116:49
#26 0x562a0ba in DataDistributor::InitActorState<DataDistributor::InitActor>::a_body1(int) /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:1083:16
#27 0x55088c0 in InitActor /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:1715:9
#28 0x55088c0 in init /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:367:26
#29 0x55088c0 in a_body1loopBody1 /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:611:39
#30 0x55088c0 in (anonymous namespace)::DataDistributionActorState<(anonymous namespace)::DataDistributionActor>::a_body1loopHead1(int) /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:2772:49
#31 0x54e9cf1 in a_body1 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:2751:16
#32 0x54e9cf1 in DataDistributionActor /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:3976:9
#33 0x54e9cf1 in dataDistribution(Reference<DataDistributor> const&, PromiseStream<GetMetricsListRequest> const&) /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:586:26
#34 0x54f8758 in a_body1 /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:1533:39
#35 0x54f8758 in DataDistributorActor /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/DataDistribution.actor.g.cpp:11473:9
#36 0x54f8758 in dataDistributor(DataDistributorInterface const&, Reference<AsyncVar<ServerDBInfo> const> const&) /mnt/ephemeral/anoyes/foundationdb/fdbserver/DataDistribution.actor.cpp:1517:26
#37 0x88f3f88 in (anonymous namespace)::WorkerServerActorState<(anonymous namespace)::WorkerServerActor>::a_body1cont10loopBody1when6(InitializeDataDistributorRequest&&, int) /mnt/ephemeral/anoyes/foundationdb/fdbserver/worker.actor.cpp:2219:42
#38 0x8871c15 in a_callback_fire /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbserver/worker.actor.g.cpp:13169:4
#39 0x8871c15 in ActorSingleCallback<(anonymous namespace)::WorkerServerActor, 6, InitializeDataDistributorRequest>::fire(InitializeDataDistributorRequest&&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:1338:34
#40 0x33e13c0 in send<InitializeDataDistributorRequest> /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:1004:29
#41 0x33e13c0 in NetNotifiedQueue<InitializeDataDistributorRequest, false>::receive(ArenaObjectReader&) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/include/fdbrpc/fdbrpc.h:702:10
#42 0xd91b6c6 in (anonymous namespace)::DeliverActorState<(anonymous namespace)::DeliverActor>::a_body1cont1(int) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/FlowTransport.actor.cpp:1042:15
#43 0xd91a37d in a_body1cont2 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbrpc/FlowTransport.actor.g.cpp:4333:15
#44 0xd91a37d in a_body1when1 /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbrpc/FlowTransport.actor.g.cpp:4345:15
#45 0xd91a37d in a_callback_fire /mnt/ephemeral/anoyes/build/foundationdb.linux.clang.asan.x86_64/fdbrpc/FlowTransport.actor.g.cpp:4366:4
#46 0xd91a37d in ActorCallback<(anonymous namespace)::DeliverActor, 0, Void>::fire(Void const&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:1316:34
#47 0x278af3f in void SAV<Void>::send<Void>(Void&&) /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:655:23
#48 0xdd2dc36 in send<Void> /mnt/ephemeral/anoyes/foundationdb/flow/include/flow/flow.h:901:8
#49 0xdd2dc36 in Sim2::execTask(Sim2::PromiseTask&) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/sim2.actor.cpp:2319:15
#50 0xdd2cf0e in Sim2::runLoop(Sim2*) /mnt/ephemeral/anoyes/foundationdb/fdbrpc/sim2.actor.cpp:1279:11
#51 0x7ebdf2e in main /mnt/ephemeral/anoyes/foundationdb/fdbserver/fdbserver.actor.cpp:2276:17
#52 0x7f62c7be6554 in __libc_start_main (/lib64/libc.so.6+0x22554)
SUMMARY: AddressSanitizer: heap-use-after-free /tmp/llvm-project/compiler-rt/lib/asan/asan_interceptors_memintrinsics.cpp:30:3 in __asan_memmove
Shadow bytes around the buggy address:
0x0c068005fef0: fa fa fd fd fd fd fa fa fd fd fd fd fa fa fd fd
0x0c068005ff00: fd fd fa fa fd fd fd fd fa fa fd fd fd fa fa fa
0x0c068005ff10: fd fd fd fd fa fa fd fd fd fd fa fa fd fd fd fd
0x0c068005ff20: fa fa fd fd fd fa fa fa fd fd fd fd fa fa fd fd
0x0c068005ff30: fd fd fa fa fd fd fd fd fa fa fd fd fd fa fa fa
=>0x0c068005ff40:[fd]fd fd fd fa fa fd fd fd fd fa fa fd fd fd fd
0x0c068005ff50: fa fa fd fd fd fa fa fa fd fd fd fa fa fa fd fd
0x0c068005ff60: fd fa fa fa fd fd fd fa fa fa fd fd fd fd fa fa
0x0c068005ff70: fd fd fd fd fa fa fd fd fd fa fa fa 00 00 00 00
0x0c068005ff80: fa fa fd fd fd fd fa fa 00 00 00 00 fa fa fd fd
0x0c068005ff90: fd fd fa fa 00 00 00 00 fa fa 00 00 00 00 fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
```
In operator= overload we need to check if the current span which is being
overwritten is eligble for serialization. If so we must send to the tracer
via the g_tracer->trace(*this) call. Previously we were incorrectly checking
the function argument o's context for sampling. This resulted in loss traces
for the NAPI:readVersionBatcher spans.
Syed Paymaan Raza