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A utility to detect memory allocation and de-allocation in a given scope. Meant to be used for testing environments.

The MemorySentinel hijacks the all the system's variants of new & delete as well malloc & free. When unarmed, it quietly monitors the memory allocation landscape without intervening (quiet infiltration). When armed, and as soon as a "transgression" is detected, the MemorySentinel will become active, and either:

• Throw a std::bad_alloc
• Log to console (while still allocating normally)
• Register the event silently (status can be queried)

MemorySentinel is very useful in Unit Tests to:

• Monitor dynamic memory allocation during certain function calls / operations
• Simulate out-of-memory conditions (e.g. branch coverage metrics)

Allocation Quota

The sentinel's strict zero-allocation-tolerance can be softened by calling setAllocationQuota(int numBytes). If this scenario the sentinel will log allocation until the quota is reached and then behave as usual.

Usage

MemorySentinel& sentinel = MemorySentinel::getInstance();
sentinel.setTransgressionBehaviour(MemorySentinel::TransgressionBehaviour::THROW_EXCEPTION);
sentinel.setArmed(true);

float* heapObject = new float[32]; // will throw an exception

// After use, disarm Sentinel
sentinel.setArmed(false);
sentinel.clearTransgressions();

Scoped usage

{
  ScopedMemorySentinel sentinel;	
  float* heapObject = new float[32];  
} 
// will assert upon exiting scope

Requirements / Compatibility

• C++14
• STL
• tested with GCC, Clang and MSVC
• tested with Catch2 Test Framework
• tested on macos, windows & linux

Status

MemorySentinel