nats.zig/deps/nats.c/examples/micro-stats.c

// Copyright 2023 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <stdio.h>
#include <stdlib.h>

#include "examples.h"

typedef struct service_state_s
{
    // in a real application this should be protected by a mutex. In this
    // example, the main control flow provides synchronization.
    int odd_count;
} service_state_t;

static microError *
handle_default(microRequest *req)
{
    char buf[64];
    const char *response = "odd";
    int n;
    service_state_t *state = microRequest_GetServiceState(req);

    snprintf(buf, sizeof(buf), "%.*s", microRequest_GetDataLength(req), microRequest_GetData(req));
    n = atoi(buf);
    if (n % 2 != 0)
    {
        // this should be protected by a mutex in a real application.
        state->odd_count++;

        response = "even";
    }
    return microRequest_Respond(req, response, strlen(response));
}

static microError *
handle_stats(microRequest *req)
{
    microError *err = NULL;
    microServiceStats *stats = NULL;
    char buf[2048];
    service_state_t *service_state = microRequest_GetServiceState(req);
    int total, custom, len;

    err = microService_GetStats(&stats, microRequest_GetService(req));
    if (err != NULL)
        return err;

    total = (int) stats->Endpoints[0].NumRequests;
    custom = service_state->odd_count;
    len = snprintf(buf, sizeof(buf),
                   "{\"total\":%d,\"odd\":%d}", total, custom);
    return microRequest_Respond(req, buf, len);
}

static microError *
run_example(natsConnection *conn, microRequestHandler stats_handler, char *buf, int buf_cap)
{
    microError *err = NULL;
    microService *m = NULL;
    microClient *c = NULL;
    service_state_t service_state = {
        .odd_count = 0,
    };
    microEndpointConfig default_cfg = {
        .Name = "default",
        .Handler = handle_default,
    };
    microServiceConfig cfg = {
        .Name = "c-stats",
        .Description = "NATS microservice in C with a custom stats handler",
        .Version = "1.0.0",
        .Endpoint = &default_cfg,
        .StatsHandler = stats_handler,
        .State = &service_state,
    };
    int i;
    int len;
    natsMsg *resp = NULL;
    natsMsg *stats_resp = NULL;

    err = micro_AddService(&m, conn, &cfg);
    if (err == NULL)
        err = micro_NewClient(&c, conn, NULL);
    for (i = 0; (err == NULL) && (i < 10); i++)
    {
        len = snprintf(buf, buf_cap, "%d", i);
        if (err == NULL)
            err = microClient_DoRequest(&resp, c, "default", buf, len);
        if (err == NULL)
            natsMsg_Destroy(resp);
    }

    if (err == NULL)
        err = microClient_DoRequest(&stats_resp, c, "$SRV.STATS.c-stats", "", 0);
    if (err == NULL)
    {
        len = natsMsg_GetDataLength(stats_resp);
        if (len > buf_cap - 1)
        {
            len = buf_cap - 1;
        }
        memcpy(buf, natsMsg_GetData(stats_resp), len);
        buf[len] = '\0';

        natsMsg_Destroy(stats_resp);
    }

    microService_Destroy(m);
    microClient_Destroy(c);
    return err;
}

int main(int argc, char **argv)
{
    microError *err = NULL;
    natsOptions *opts = parseArgs(argc, argv, "");
    natsConnection *conn = NULL;
    char buf[2048];

    err = micro_ErrorFromStatus(
        natsConnection_Connect(&conn, opts));
    if (err == NULL)
        err = run_example(conn, NULL, buf, sizeof(buf));
    if (err == NULL)
        printf("Default stats response:\n----\n%s\n----\n\n", buf);

    if (err == NULL)
        err = run_example(conn, handle_stats, buf, sizeof(buf));
    if (err == NULL)
        printf("Custom stats response:\n----\n%s\n----\n\n", buf);

    if (err != NULL)
    {
        fprintf(stderr, "Error: %s\n", microError_String(err, buf, sizeof(buf)));
    }

    natsOptions_Destroy(opts);
    natsConnection_Destroy(conn);
    microError_Destroy(err);
    return err == NULL ? 0 : 1;
}