Macos

Process CPU and memory sampling on macOS. The declarations in lfmacos.h are available only on Apple platforms, and CMake builds the implementation only there.

Usage

Create a sample with new_ProcessData(), then call update_process() at intervals. The first successful update establishes a baseline and reports zero CPU usage.

ProcessData *pd = new_ProcessData();
if (pd != NULL) {
    for (int i = 0; i < 10; i++) {
        if (update_process(getpid(), pd) != 0) {
            break;
        }
        printf("CPU: %.2f\n", pd->percent_cpu);
        sleep(1);
    }
    destroy_ProcessData(pd);
}

Call destroy_ProcessData() when finished to free the sample.

Structs

ProcessData

CPU and memory measurements for a process. Use the same process ID for successive updates of a sample.

typedef struct {
    double total_user_time;
    double total_kernel_time;
    double last_total_consumed;
    double percent_cpu;

    uint64_t virtual_memory;
    uint64_t resident_memory;

    time_t timestamp;
    time_t last_timestamp;
} ProcessData;

Members:

• total_user_time, total_kernel_time: Cumulative CPU time in seconds
• last_total_consumed: CPU time at the previous update, or -1.0 before the first update
• percent_cpu: CPU time consumed divided by elapsed wall time, multiplied by 100; can exceed 100 for a process using multiple cores
• virtual_memory, resident_memory: Memory sizes in bytes
• timestamp, last_timestamp: Wall-clock timestamps used to measure the interval; both hold the current sample time after a successful update

Functions

new_ProcessData

Allocates a sample with last_total_consumed set to -1.0 and all other fields zero. Returns NULL on allocation failure.

ProcessData *new_ProcessData(void);

destroy_ProcessData

Frees the sample. Safe to call with NULL.

void destroy_ProcessData(ProcessData *pd);

update_process

Updates CPU and memory measurements for pid. Returns 0 on success or -1 if proc is NULL or the system queries fail.

CPU usage is measured over whole wall-clock seconds. The first update, or an update with no positive elapsed interval, reports zero CPU usage. Space updates at least one second apart to obtain a useful interval.

int update_process(pid_t pid, ProcessData *proc);