Refactor Makefile and enhance disk/memory eviction tests

- Updated the 'bench' target in the Makefile to run all benchmarks for MemoryFS and DiskFS, improving clarity and coverage.
- Added explicit post-eviction consistency checks in DiskFS tests to ensure on-disk files are removed after eviction.
- Introduced new benchmarks for memory eviction strategies under pressure, enhancing test coverage for memory management.
- Improved error handling in benchmark tests for both disk and memory file systems, ensuring robustness during performance evaluations.
- Refactored key generation in tests for consistency and clarity.

vfs/memory/memory.go

@@ -357,6 +357,9 @@ func (m *MemoryFS) EvictBySize(bytesNeeded uint, ascending bool) uint {
 	var candidates []evictCandidate
 	for key, fi := range m.info {
 		candidates = append(candidates, evictCandidate{key: key, size: fi.Size})
+		if len(candidates) >= maxEvictBatch {
+			break
+		}
 	}
 	m.mu.RUnlock()
 
@@ -405,6 +408,9 @@ func (m *MemoryFS) EvictFIFO(bytesNeeded uint) uint {
 			key   string
 			cTime time.Time
 		}{key: key, cTime: fi.CTime})
+		if len(candidates) >= maxEvictBatch {
+			break
+		}
 	}
 	m.mu.RUnlock()
 
@@ -451,6 +457,9 @@ func (m *MemoryFS) EvictLFU(bytesNeeded uint) uint {
 			accessCount int
 			aTime       time.Time
 		}{key: key, accessCount: fi.AccessCount, aTime: fi.ATime})
+		if len(candidates) >= maxEvictBatch {
+			break
+		}
 	}
 	m.mu.RUnlock()
 
@@ -502,6 +511,9 @@ func (m *MemoryFS) EvictHybrid(bytesNeeded uint) uint {
 			accessCount int
 			aTime       time.Time
 		}{key: key, accessCount: fi.AccessCount, aTime: fi.ATime})
+		if len(candidates) >= maxEvictBatch {
+			break
+		}
 	}
 	m.mu.RUnlock()