libflint/docs/macos.md

# macOS

Platform-specific code for macOS. Everything in this module, including the headers, is wrapped in the following
preprocessor macro

```c
#if defined(__APPLE__) || defined(__MACH__)
/* 
... code ...
*/
#endif /* defined(__APPLE__) || defined(__MACH__) */
```

## Structs

### ProcessData

ProcessData is a struct that tracks cpu and memory usage of a process. It needs to be regularly updated with calls to
`update_process()` in order to provide accurate information

```c
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;
```

## Functions

## new_ProcessData

Returns a pointer to a `ProcessData` struct.

```c
ProcessData *new_ProcessData();
```

## update_process

Updates a `ProcessData` struct. This should be called in a loop or at specific intervals to measure proper usage
data. An example is below

```c
int update_process(pid_t pid, ProcessData *proc);

/* Example */
pid_t pid = getpid();
ProcessData *pd = new_ProcessData();
for (int i = 0; i < 10; i++) {
    update_process(pid, pd);
    printf("CPU: %.2f\n", pd->percent_cpu);
    sleep(1);
}
free(pd);
```

## reallocarray

reallocarray is reimplemented for macOS because Apple doesn't expose their implementation. This is taken straight
from the OpenBSD source

```c
void *reallocarray(void *optr, size_t nmemb, size_t size);
```