Ensure correct behavior when epsilon is 0 and use constant for magic number.

2 files changed, 9 insertions, 7 deletions

diff --git a/staging_vespalib/src/tests/util/process_memory_stats/process_memory_stats_test.cpp b/staging_vespalib/src/tests/util/process_memory_stats/process_memory_stats_test.cpp
index 6210acb1f1a..45e75547fb2 100644
--- a/staging_vespalib/src/tests/util/process_memory_stats/process_memory_stats_test.cpp
+++ b/staging_vespalib/src/tests/util/process_memory_stats/process_memory_stats_test.cpp
@@ -13,6 +13,8 @@ using namespace vespalib;
 
 namespace {
 
+constexpr uint64_t SIZE_EPSILON = 4095;
+
 std::string toString(const ProcessMemoryStats &stats)
 {
     std::ostringstream os;
@@ -27,7 +29,7 @@ std::string toString(const ProcessMemoryStats &stats)
 
 TEST("Simple stats")
 {
-    ProcessMemoryStats stats(ProcessMemoryStats::create(4096));
+    ProcessMemoryStats stats(ProcessMemoryStats::create(SIZE_EPSILON));
     std::cout << toString(stats) << std::endl;
     EXPECT_LESS(0u, stats.getMappedVirt());
     EXPECT_LESS(0u, stats.getMappedRss());
@@ -37,7 +39,7 @@ TEST("Simple stats")
 
 TEST("grow anonymous memory")
 {
-    ProcessMemoryStats stats1(ProcessMemoryStats::create(4096));
+    ProcessMemoryStats stats1(ProcessMemoryStats::create(SIZE_EPSILON));
     std::cout << toString(stats1) << std::endl;
     size_t mapLen = 64 * 1024;
     void *mapAddr = mmap(nullptr, mapLen, PROT_READ | PROT_WRITE,
@@ -48,7 +50,7 @@ TEST("grow anonymous memory")
     EXPECT_LESS_EQUAL(stats1.getAnonymousVirt() + mapLen,
                       stats2.getAnonymousVirt());
     memset(mapAddr, 1, mapLen);
-    ProcessMemoryStats stats3(ProcessMemoryStats::create(4096));
+    ProcessMemoryStats stats3(ProcessMemoryStats::create(SIZE_EPSILON));
     std::cout << toString(stats3) << std::endl;
     // Cannot check that resident grows if swap is enabled and system loaded
     munmap(mapAddr, mapLen);
@@ -63,16 +65,16 @@ TEST("grow mapped memory")
     of.close();
     int mapfileFileDescriptor = open("mapfile", O_RDONLY, 0666);
     EXPECT_LESS_EQUAL(0, mapfileFileDescriptor);
-    ProcessMemoryStats stats1(ProcessMemoryStats::create(4096));
+    ProcessMemoryStats stats1(ProcessMemoryStats::create(SIZE_EPSILON));
     std::cout << toString(stats1) << std::endl;
     void *mapAddr = mmap(nullptr, mapLen, PROT_READ, MAP_SHARED,
                          mapfileFileDescriptor, 0);
     EXPECT_NOT_EQUAL(reinterpret_cast<void *>(-1), mapAddr);
-    ProcessMemoryStats stats2(ProcessMemoryStats::create(4096));
+    ProcessMemoryStats stats2(ProcessMemoryStats::create(SIZE_EPSILON));
     std::cout << toString(stats2) << std::endl;
     EXPECT_LESS_EQUAL(stats1.getMappedVirt() + mapLen, stats2.getMappedVirt());
     EXPECT_EQUAL(0, memcmp(mapAddr, &buf[0], mapLen));
-    ProcessMemoryStats stats3(ProcessMemoryStats::create(4096));
+    ProcessMemoryStats stats3(ProcessMemoryStats::create(SIZE_EPSILON));
     std::cout << toString(stats3) << std::endl;
     // Cannot check that resident grows if swap is enabled and system loaded
     munmap(mapAddr, mapLen);
diff --git a/staging_vespalib/src/vespa/vespalib/util/process_memory_stats.cpp b/staging_vespalib/src/vespa/vespalib/util/process_memory_stats.cpp
index 13e2b3085ca..b94e35407a1 100644
--- a/staging_vespalib/src/vespa/vespalib/util/process_memory_stats.cpp
+++ b/staging_vespalib/src/vespa/vespalib/util/process_memory_stats.cpp
@@ -152,7 +152,7 @@ namespace {
 bool
 similar(uint64_t lhs, uint64_t rhs, uint64_t epsilon)
 {
-    return (lhs < rhs) ? ((rhs - lhs) < epsilon) : ((lhs - rhs) < epsilon);
+    return (lhs < rhs) ? ((rhs - lhs) <= epsilon) : ((lhs - rhs) <= epsilon);
 }
 
 }