Examples Collapse

Collapse example

Collapse

This example shows how to collapse repeated log messages.

What it demonstrates

• LogmeD_Collapse(...) / LogmeD_CollapseIgnore(...)
• LogmeI_Collapse(...) / LogmeI_CollapseIgnore(...)
• LogmeW_Collapse(...) / LogmeW_CollapseIgnore(...)
• LogmeE_Collapse(...) / LogmeE_CollapseIgnore(...)
• LogmeC_Collapse(...) / LogmeC_CollapseIgnore(...)

Notes

• LogmeX_Collapse(limit, ...) uses the formatted message text as the repeat key.
• LogmeX_CollapseIgnore(ignoreRegex, limit, ...) removes all substrings matching ignoreRegex from the formatted message before comparing it with the previous message.
• LogmeX_CollapseIgnore(...) is intended for volatile fields such as request IDs, correlation IDs, timestamps, or counters.
• LogmeX_CollapseIgnore(...) prints the original formatted message. The regular expression is used only for comparison.
• X is one of the usual log levels: D, I, W, E, or C.
• The first message is printed immediately.
• Repeated messages are skipped until the repeat counter reaches limit.
• When the limit is reached, logme prints one message with the repeat counter and then starts counting again.

Console output

2026-06-03 16:33:08:794 W SameText(): network error: connection refused
2026-06-03 16:33:08:797 W SameText(): repeated 3 times: network error: connection refused
2026-06-03 16:33:08:797 E Error: IgnoreCorrelationId(): request failed: correlation-id=0, network error: connection refused
2026-06-03 16:33:08:797 E Error: IgnoreCorrelationId(): repeated 2 times: request failed: correlation-id=2, network error: connection refused

Source code

Sources

Repository folder: examples/Collapse

ExampleCollapse.cpp

Open in repository

#include <Logme/Logme.h>

static void SameText()
{
  for (int i = 0; i < 4; i++)
  {
    LogmeW_Collapse(3, "network error: connection refused");
  }
}

static void IgnoreCorrelationId()
{
  for (int i = 0; i < 3; i++)
  {
    LogmeE_CollapseIgnore(
      "correlation-id=[0-9]+"
      , 2
      , "request failed: correlation-id=%d, network error: connection refused"
      , i
    );
  }
}

int main()
{
  SameText();
  IgnoreCorrelationId();

  return 0;
}

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