#!/usr/sbin/bpftrace

// Monitor the start of HTTP request processing
uprobe:/usr/sbin/nginx:ngx_http_process_request
{
    printf("HTTP request processing started (tid: %d)\n", tid);
    @start[tid] = nsecs;
}

// Monitor when an HTTP request is finalized
uretprobe:/usr/sbin/nginx:ngx_http_finalize_request
/@start[tid]/
{
    $elapsed = nsecs - @start[tid];
    printf("HTTP request processed in %d ns (tid: %d)\n", $elapsed, tid);
    delete(@start[tid]);
}

// Monitor the start of sending a request to an upstream server
uprobe:/usr/sbin/nginx:ngx_http_upstream_send_request
{
    printf("Upstream request sending started (tid: %d)\n", tid);
    @upstream_start[tid] = nsecs;
}

// Monitor when the upstream request is sent
uretprobe:/usr/sbin/nginx:ngx_http_upstream_send_request
/@upstream_start[tid]/
{
    $elapsed = nsecs - @upstream_start[tid];
    printf("Upstream request sent in %d ns (tid: %d)\n", $elapsed, tid);
    delete(@upstream_start[tid]);
}

// Monitor the start of event processing
uprobe:/usr/sbin/nginx:ngx_event_process_posted
{
    printf("Event processing started (tid: %d)\n", tid);
    @event_start[tid] = nsecs;
}

// Monitor when event processing is completed
uretprobe:/usr/sbin/nginx:ngx_event_process_posted
/@event_start[tid]/
{
    $elapsed = nsecs - @event_start[tid];
    printf("Event processed in %d ns (tid: %d)\n", $elapsed, tid);
    delete(@event_start[tid]);
}