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handle_paxos_accept() fails to record a trace message when done with handling #18725

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tchaikov opened this issue May 17, 2024 · 0 comments
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Backport candidate backport/5.4 Issues that should be backported to 5.4 branch once they'll be fixed
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@tchaikov
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clang-tidy warns:

Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^

this is not a false positive. as tr_state is a captured by move for constructing a variable in the captured list of a lambda which is in turn passed to the expression evaluated to f.

even the expression itself is not evaluated yet when we reference tr_state to check if it is empty after preparing the expression,
tr_state is already moved away into the captured variable. so at that moment, the statement of f = f.finally(...) is never evaluated, because tr_state is always empty by then.

so the trace message in the finally() block is never recorded.

@tchaikov tchaikov self-assigned this May 17, 2024
tchaikov added a commit to tchaikov/scylladb that referenced this issue May 17, 2024
…ept()

this change is inspired by following warning from clang-tidy

```
Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^
```

this is not a false positive. as `tr_state` is a captured by move for
constructing a variable in the captured list of a lambda which is in
turn passed to the expression evaluated to `f`.

even the expression itself is not evaluated yet when we reference
`tr_state` to check if it is empty after preparing the expression,
`tr_state` is already moved away into the captured variable. so
at that moment, the statement of `f = f.finally(...)` is never
evaluated, because `tr_state` is always empty by then.

so before this change, the trace message is never recorded.

in this change, we address this issue by capturing `tr_state` by
copying it. as `tr_state` is backed by a `lw_shared_ptr`, the overhead is
neglectable.

after this change, the tracing message is recorded.

please note, we could coroutinize this function to improve its
readability, but since this is a fix and should be backported,
let's start with a minimal fix, and worry about the readability
in a follow-up change.

Fixes scylladb#18725
Signed-off-by: Kefu Chai <[email protected]>
tchaikov added a commit to tchaikov/scylladb that referenced this issue May 17, 2024
…ept()

this change is inspired by following warning from clang-tidy

```
Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^
```

this is not a false positive. as `tr_state` is a captured by move for
constructing a variable in the captured list of a lambda which is in
turn passed to the expression evaluated to `f`.

even the expression itself is not evaluated yet when we reference
`tr_state` to check if it is empty after preparing the expression,
`tr_state` is already moved away into the captured variable. so
at that moment, the statement of `f = f.finally(...)` is never
evaluated, because `tr_state` is always empty by then.

so before this change, the trace message is never recorded.

in this change, we address this issue by capturing `tr_state` by
copying it. as `tr_state` is backed by a `lw_shared_ptr`, the overhead is
neglectable.

after this change, the tracing message is recorded.

please note, we could coroutinize this function to improve its
readability, but since this is a fix and should be backported,
let's start with a minimal fix, and worry about the readability
in a follow-up change.

Fixes scylladb#18725
Signed-off-by: Kefu Chai <[email protected]>
tchaikov added a commit to tchaikov/scylladb that referenced this issue May 17, 2024
…ept()

this change is inspired by following warning from clang-tidy

```
Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^
```

this is not a false positive. as `tr_state` is a captured by move for
constructing a variable in the captured list of a lambda which is in
turn passed to the expression evaluated to `f`.

even the expression itself is not evaluated yet when we reference
`tr_state` to check if it is empty after preparing the expression,
`tr_state` is already moved away into the captured variable. so
at that moment, the statement of `f = f.finally(...)` is never
evaluated, because `tr_state` is always empty by then.

so before this change, the trace message is never recorded.

in this change, we address this issue by capturing `tr_state` by
copying it. as `tr_state` is backed by a `lw_shared_ptr`, the overhead is
neglectable.

after this change, the tracing message is recorded.

the change introduced this issue was 548767f.

please note, we could coroutinize this function to improve its
readability, but since this is a fix and should be backported,
let's start with a minimal fix, and worry about the readability
in a follow-up change.

Refs 548767f
Fixes scylladb#18725
Signed-off-by: Kefu Chai <[email protected]>
@tchaikov tchaikov added backport/5.2 backport/5.4 Issues that should be backported to 5.4 branch once they'll be fixed labels May 17, 2024
@mykaul mykaul added this to the 6.0 milestone May 19, 2024
mergify bot pushed a commit that referenced this issue May 20, 2024
…ept()

this change is inspired by following warning from clang-tidy

```
Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^
```

this is not a false positive. as `tr_state` is a captured by move for
constructing a variable in the captured list of a lambda which is in
turn passed to the expression evaluated to `f`.

even the expression itself is not evaluated yet when we reference
`tr_state` to check if it is empty after preparing the expression,
`tr_state` is already moved away into the captured variable. so
at that moment, the statement of `f = f.finally(...)` is never
evaluated, because `tr_state` is always empty by then.

so before this change, the trace message is never recorded.

in this change, we address this issue by capturing `tr_state` by
copying it. as `tr_state` is backed by a `lw_shared_ptr`, the overhead is
neglectable.

after this change, the tracing message is recorded.

the change introduced this issue was 548767f.

please note, we could coroutinize this function to improve its
readability, but since this is a fix and should be backported,
let's start with a minimal fix, and worry about the readability
in a follow-up change.

Refs 548767f
Fixes #18725
Signed-off-by: Kefu Chai <[email protected]>
(cherry picked from commit a429e7b)

# Conflicts:
#	service/storage_proxy.cc
mergify bot pushed a commit that referenced this issue May 20, 2024
…ept()

this change is inspired by following warning from clang-tidy

```
Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^
```

this is not a false positive. as `tr_state` is a captured by move for
constructing a variable in the captured list of a lambda which is in
turn passed to the expression evaluated to `f`.

even the expression itself is not evaluated yet when we reference
`tr_state` to check if it is empty after preparing the expression,
`tr_state` is already moved away into the captured variable. so
at that moment, the statement of `f = f.finally(...)` is never
evaluated, because `tr_state` is always empty by then.

so before this change, the trace message is never recorded.

in this change, we address this issue by capturing `tr_state` by
copying it. as `tr_state` is backed by a `lw_shared_ptr`, the overhead is
neglectable.

after this change, the tracing message is recorded.

the change introduced this issue was 548767f.

please note, we could coroutinize this function to improve its
readability, but since this is a fix and should be backported,
let's start with a minimal fix, and worry about the readability
in a follow-up change.

Refs 548767f
Fixes #18725
Signed-off-by: Kefu Chai <[email protected]>
(cherry picked from commit a429e7b)
denesb pushed a commit that referenced this issue May 21, 2024
…ept()

this change is inspired by following warning from clang-tidy

```
Warning: /home/runner/work/scylladb/scylladb/service/storage_proxy.cc:884:13: warning: 'tr_state' used after it was moved [bugprone-use-after-move]
  884 |         if (tr_state) {
      |             ^
/home/runner/work/scylladb/scylladb/service/storage_proxy.cc:872:139: note: move occurred here
  872 |         auto f = get_schema_for_read(proposal.update.schema_version(), src_addr, *timeout).then([&sp = _sp, &sys_ks = _sys_ks, tr_state = std::move(tr_state),
      |                                                                                                                                           ^
```

this is not a false positive. as `tr_state` is a captured by move for
constructing a variable in the captured list of a lambda which is in
turn passed to the expression evaluated to `f`.

even the expression itself is not evaluated yet when we reference
`tr_state` to check if it is empty after preparing the expression,
`tr_state` is already moved away into the captured variable. so
at that moment, the statement of `f = f.finally(...)` is never
evaluated, because `tr_state` is always empty by then.

so before this change, the trace message is never recorded.

in this change, we address this issue by capturing `tr_state` by
copying it. as `tr_state` is backed by a `lw_shared_ptr`, the overhead is
neglectable.

after this change, the tracing message is recorded.

the change introduced this issue was 548767f.

please note, we could coroutinize this function to improve its
readability, but since this is a fix and should be backported,
let's start with a minimal fix, and worry about the readability
in a follow-up change.

Refs 548767f
Fixes #18725
Signed-off-by: Kefu Chai <[email protected]>
(cherry picked from commit a429e7b)

Closes #18763
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