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Suppression file name cache. #8684

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f45c7cb
Suppression file name cache.
MartinBP Jul 1, 2026
1e97436
Fix naming violation of private member variable.
MartinBP Jul 1, 2026
3693c19
Rename local variable to avoid conflict with function name [shadowFun…
MartinBP Jul 1, 2026
c0ed56d
Implement performance test for large number of violations and suppres…
MartinBP Jul 4, 2026
51aecc6
Skip 'test_large_number_of_violations_and_suppressions' on macOS beca…
MartinBP Jul 4, 2026
715c90e
Double the pytest timeout for test_large_number_of_violations_and_sup…
MartinBP Jul 4, 2026
fd3ac4d
Merge branch 'main' into suppression-filename-cache
MartinBP Aug 21, 2026
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17 changes: 16 additions & 1 deletion lib/suppressions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -420,7 +420,7 @@ SuppressionList::Suppression::Result SuppressionList::Suppression::isSuppressed(
if (!thisAndNextLine || lineNumber + 1 != errmsg.lineNumber)
return Result::None;
}
if (!fileName.empty() && !PathMatch::match(fileName, errmsg.getFileName()))
if (!fileName.empty() && !isFileNameMatch(errmsg.getFileName()))
return Result::None;
if (hash > 0 && hash != errmsg.hash)
return Result::Checked;
Expand Down Expand Up @@ -453,6 +453,21 @@ SuppressionList::Suppression::Result SuppressionList::Suppression::isSuppressed(
return Result::Matched;
}

bool SuppressionList::Suppression::isFileNameMatch(const std::string &errorFileName) const
{
const auto it = mFileNameMatchCache.find(errorFileName);

@danmar danmar Aug 20, 2026 •
edited
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I fear there could be thread safety issues if two threads call isFileNameMatch at the same time. Could there?
I think either some locking will be needed. Or we need to move the cache data to each analyzer thread.

To complicate things a bit we sometimes run processes and sometimes threads. I am not sure how this will work when processes are used but I assume this cache will only work per-process then, each process will get its own cache..

@MartinBP MartinBP Aug 21, 2026

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Thanks for your feedback.

A std::map is not thread safe, so if multiple threads can/will update it at the same time then it must be protected by a mutex.
The other members of the Suppression class are not protected by a lock, which is why I didn't create one in the first place, but I suppose this could be because they are either primitive types or are only written to during initial creation of a suppression.

I see no problem with each process having it's own cache (if that is the case) because it will still reduce the total amount of calls to PathMatch::match, which is the whole goal with the cache.

I will work on a mutex to protect the cache to eliminate any concerns about thread safety issues.

@MartinBP MartinBP Aug 21, 2026

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I spent time some time looking at the code again, and the cache - including all other members in the Suppression struct/class - are already protected by the mutex declared in SuppressionList.

All calls to Suppression.isFileNameMatch are routed through SuppressionsList.isSuppressed, which acquires the lock.
The only exception is a single place in some test code.
This test code has a todo, which could indicate that it needs to be changed.
Code copied below (see testsuppressions.cpp).

    // TODO: this tests an internal function - should it be private?
    void symbol() const {
        SuppressionList::Suppression s;
        s.fileName = "test.cpp";
        s.errorId = "foo";
        s.symbolName = "array*";

        SuppressionList::ErrorMessage errorMsg;
        errorMsg.errorId = "foo";
        errorMsg.symbolNames = "";
        ASSERT_EQUALS_ENUM(SuppressionList::Suppression::Result::None, s.isSuppressed(errorMsg));
        errorMsg.setFileName("test.cpp");
        errorMsg.lineNumber = 123;
        ASSERT_EQUALS_ENUM(SuppressionList::Suppression::Result::Checked, s.isSuppressed(errorMsg));
        errorMsg.symbolNames = "x\n";
        ASSERT_EQUALS_ENUM(SuppressionList::Suppression::Result::Checked, s.isSuppressed(errorMsg));
        errorMsg.symbolNames = "array1\n";
        ASSERT_EQUALS_ENUM(SuppressionList::Suppression::Result::Matched, s.isSuppressed(errorMsg));
        errorMsg.symbolNames = "x\n"
                               "array2\n";
        ASSERT_EQUALS_ENUM(SuppressionList::Suppression::Result::Matched, s.isSuppressed(errorMsg));
        errorMsg.symbolNames = "array3\n"
                               "x\n";
        ASSERT_EQUALS_ENUM(SuppressionList::Suppression::Result::Matched, s.isSuppressed(errorMsg));
    }

This means that someone has already thought about potential thread safety issues related to the suppression list and handled it accordingly, which is a good thing 👍

if (it != mFileNameMatchCache.end())
return it->second;

const bool result = PathMatch::match(fileName, errorFileName);

if (mFileNameMatchCache.size() >= mFileNameMatchCacheMaxEntries)
mFileNameMatchCache.clear();

mFileNameMatchCache.emplace(errorFileName, result);
return result;
}

bool SuppressionList::Suppression::isMatch(const SuppressionList::ErrorMessage &errmsg)
{
switch (isSuppressed(errmsg)) {
Expand Down
6 changes: 6 additions & 0 deletions lib/suppressions.h
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,12 @@ class CPPCHECKLIB SuppressionList {
bool isPolyspace{};

enum : std::int8_t { NO_LINE = -1 };

private:
bool isFileNameMatch(const std::string &errorFileName) const;

static constexpr std::size_t mFileNameMatchCacheMaxEntries = 256;
mutable std::map<std::string, bool> mFileNameMatchCache;
};

/**
Expand Down
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