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[SourceKit] Support cancellation of requests while an AST is being built #38782

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Merged
merged 2 commits into from
Sep 28, 2021
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[SourceKit] Support cancellation of requests while an AST is being built #38782

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998a787
[Sema] Add cancellation flag to typechecker options
ahoppen Aug 5, 2021
7a80034
[SourceKit] Support cancellation of requests while an AST is being built
ahoppen Aug 9, 2021
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6 changes: 6 additions & 0 deletions include/swift/Basic/LangOptions.h
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Expand Up @@ -595,6 +595,12 @@ namespace swift {
/// than this many seconds.
unsigned ExpressionTimeoutThreshold = 600;

/// If the shared pointer is not a \c nullptr and the pointee is \c true,
/// typechecking should be aborted at the next possible opportunity.
/// This is used by SourceKit to cancel requests for which the result is no
/// longer of interest.
std::shared_ptr<std::atomic<bool>> CancellationFlag = nullptr;
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@xedin or @hborla any concerns about this mutable state living in TypeCheckerOptions?

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I don't have concerns but I've also never touched this thing 🙂 @CodaFi do you have any thoughts?

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It’s a fine place to put it to start. I just hope we move off a cooperative cancellation model and push this into the request evaluator at some point.


/// If non-zero, abort the switch statement exhaustiveness checker if
/// the Space::minus function is called more than this many times.
///
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4 changes: 4 additions & 0 deletions include/swift/Sema/ConstraintSystem.h
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Expand Up @@ -5155,6 +5155,10 @@ class ConstraintSystem {
if (isExpressionAlreadyTooComplex)
return true;

auto CancellationFlag = getASTContext().TypeCheckerOpts.CancellationFlag;
if (CancellationFlag && CancellationFlag->load(std::memory_order_relaxed))
return true;

auto used = getASTContext().getSolverMemory() + solutionMemory;
MaxMemory = std::max(used, MaxMemory);
auto threshold = getASTContext().TypeCheckerOpts.SolverMemoryThreshold;
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15 changes: 13 additions & 2 deletions test/SourceKit/Misc/stats.swift
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Expand Up @@ -46,8 +46,8 @@ func foo() {}
// SEMA_3: 1 {{.*}} source.statistic.num-ast-builds
// SEMA_3: 1 {{.*}} source.statistic.num-asts-in-memory
// SEMA_3: 1 {{.*}} source.statistic.max-asts-in-memory
// SEMA_3: 0 {{.*}} source.statistic.num-ast-cache-hits
// SEMA_3: 1 {{.*}} source.statistic.num-ast-snaphost-uses
// SEMA_3: 1 {{.*}} source.statistic.num-ast-cache-hits
// SEMA_3: 0 {{.*}} source.statistic.num-ast-snaphost-uses

// RUN: %sourcekitd-test -req=sema %s -- -Xfrontend -disable-implicit-concurrency-module-import %s == -req=related-idents -pos=1:6 %s -- -Xfrontend -disable-implicit-concurrency-module-import %s == -req=stats | %FileCheck %s -check-prefix=SEMA_4

Expand All @@ -58,3 +58,14 @@ func foo() {}
// SEMA_4: 1 {{.*}} source.statistic.max-asts-in-memory
// SEMA_4: 1 {{.*}} source.statistic.num-ast-cache-hits
// SEMA_4: 0 {{.*}} source.statistic.num-ast-snaphost-uses

// Test that we can have two files open and don't need to rebuild an AST when doing the cursor info request on '%s' after opening '10bytes.swift'
// RUN: %sourcekitd-test \
// RUN: -req=sema %s -- -Xfrontend -disable-implicit-concurrency-module-import %s == \
// RUN: -req=sema %S/Inputs/10bytes.swift -- -Xfrontend -disable-implicit-concurrency-module-import %S/Inputs/10bytes.swift == \
// RUN: -req=cursor -pos=1:6 %s -- -Xfrontend -disable-implicit-concurrency-module-import %s == \
// RUN: -req=stats | %FileCheck %s -check-prefix=OPEN_TWO_FILES

// OPEN_TWO_FILES: 2 {{.*}} source.statistic.num-ast-builds
// OPEN_TWO_FILES: 2 {{.*}} source.statistic.num-asts-in-memory
// OPEN_TWO_FILES: 2 {{.*}} source.statistic.max-asts-in-memory
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