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load_balancers.c
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load_balancers.c
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#include "http_server.h"
#ifdef ROUND_ROBIN
char* round_robin(){
pthread_mutex_lock(&lb_state_mutex);
servers_container->last_served_index++;
if (servers_container->last_served_index == 4) {
servers_container->last_served_index=0;
}
pthread_mutex_unlock(&lb_state_mutex);
return servers_container->servers[servers_container->last_served_index].ipaddress;
}
int init_server_container(AppServerContainer** container_ptr){
*container_ptr = (AppServerContainer*)malloc(sizeof(AppServerContainer));
(*container_ptr)->last_served_index = 3;
init_server_struct(&((*container_ptr)->servers[0]), S2ELAB_IP);
init_server_struct(&((*container_ptr)->servers[1]), S2ELABSTUDENT_IP);
init_server_struct(&((*container_ptr)->servers[2]), S2ELABTEACHER_IP);
init_server_struct(&((*container_ptr)->servers[3]), S2ELABTUTOR_IP);
return 0;
}
#endif
#ifdef LEAST_CONN
char* least_conn(int* served_by_idx){
pthread_mutex_lock(&lb_state_mutex);
int i, least_conn_index=0;
int least_conn_value=servers_container->now_serving[0];
for (i=1; i<=3; i++){
if (servers_container->now_serving[i] < least_conn_value){
least_conn_index = i;
least_conn_value = servers_container->now_serving[i];
}
}
/// printf("NOW SERVING DISTRIBUTION: %d %d %d %d\n", servers_container->now_serving[0], servers_container->now_serving[1], servers_container->now_serving[2], servers_container->now_serving[3]);
servers_container->now_serving[least_conn_index]++;
*served_by_idx=least_conn_index;
pthread_mutex_unlock(&lb_state_mutex);
return servers_container->servers[least_conn_index].ipaddress;
}
int init_server_container(AppServerContainer** container_ptr){
*container_ptr = (AppServerContainer*)malloc(sizeof(AppServerContainer));
(*container_ptr)->now_serving[0]=0;
(*container_ptr)->now_serving[1]=0;
(*container_ptr)->now_serving[2]=0;
(*container_ptr)->now_serving[3]=0;
init_server_struct(&((*container_ptr)->servers[0]), S2ELAB_IP);
init_server_struct(&((*container_ptr)->servers[1]), S2ELABSTUDENT_IP);
init_server_struct(&((*container_ptr)->servers[2]), S2ELABTEACHER_IP);
init_server_struct(&((*container_ptr)->servers[3]), S2ELABTUTOR_IP);
return 0;
}
#endif
#ifdef LEAST_LATENCY
char* least_latency(int* served_by_idx){
int r = rand() % servers_container->weight[3];
if (r < servers_container->weight[0]){
return servers_container->servers[0].ipaddress;
}
else if (r < servers_container->weight[1]){
return servers_container->servers[1].ipaddress;
}
else if (r < servers_container->weight[2]){
return servers_container->servers[2].ipaddress;
}
if (r < servers_container->weight[3]){
return servers_container->servers[3].ipaddress;
}
}
int init_server_container(AppServerContainer** container_ptr){
*container_ptr = (AppServerContainer*)malloc(sizeof(AppServerContainer));
(*container_ptr)->weight[0]=0;
(*container_ptr)->weight[1]=0;
(*container_ptr)->weight[2]=0;
(*container_ptr)->weight[3]=0;
(*container_ptr)->time[0]=100;
(*container_ptr)->time[1]=100;
(*container_ptr)->time[2]=100;
(*container_ptr)->time[3]=100;
init_server_struct(&((*container_ptr)->servers[0]), S2ELAB_IP);
init_server_struct(&((*container_ptr)->servers[1]), S2ELABSTUDENT_IP);
init_server_struct(&((*container_ptr)->servers[2]), S2ELABTEACHER_IP);
init_server_struct(&((*container_ptr)->servers[3]), S2ELABTUTOR_IP);
return 0;
}
size_t ignore_response(char* ptr, size_t size, size_t nmemb, void* userdata){
// override default libcurl behavior and do not print output to stdout
return size*nmemb;
}
int perform_dummy_request(char* ipaddr){
CURL *curl;
CURLcode res;
char response_str[5000];
curl = curl_easy_init();
clock_t t;
printf("Performing dummy request on %s\n", ipaddr);
if (curl) {
curl_easy_setopt(curl, CURLOPT_URL, ipaddr);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, ignore_response);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void*)response_str);
t = clock();
res = curl_easy_perform(curl);
t = clock() - t;
if (res != CURLE_OK) {
fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
}
curl_easy_cleanup(curl);
return t;
}
}
void weight_calculator(){
int i;
float temp_weights[4], total_weight;
clock_t tmp_t, t[4], total_t;
while(1){
total_t = 0;
total_weight = 0.0;
for(i=0; i<4; i++){
char ping_cmd[64];
// sprintf(ping_cmd, "ping -c 1 %s | tail -1 | awk -F '/' '{print $5}'", servers_container->servers[i].ipaddress);
sprintf(ping_cmd, "curl --silent -o /dev/null %s -w %%{time_total}\\n", servers_container->servers[i].ipaddress);
FILE *ping = popen(ping_cmd, "r");
char res[8];
fgets(res, sizeof(res), ping);
t[i] = (1000 * atof(res) + servers_container->time[i]) / 2;
if (t[i]<100){
t[i] = 100;
}
else if (t[i]>10000){
t[i] = 10000;
}
servers_container->time[i] = t[i];
pclose(ping);
printf("time passed: %d\n", (int)t[i]);
total_t += t[i];
}
// printf("total time: %d\n", (int)total_t);
servers_container->weight[0] = round(100*((float)((float)total_t/(float)t[0])));
for(i=1; i<4; i++){
servers_container->weight[i] = round(100*((float)((float)total_t/(float)t[i]))) + servers_container->weight[i-1];
// total_weight += temp_weights[i];
}
// printf("Servers tmp_weights: %f %f %f %f, total weight is %f\n", temp_weights[0], temp_weights[1], temp_weights[2], temp_weights[3], total_weight);
printf("Servers weights: %d %d %d %d\n", servers_container->weight[0], servers_container->weight[1], servers_container->weight[2], servers_container->weight[3]);
// pthread_mutex_unlock(&lb_state_mutex);
sleep(SEC_INTERVAL);
}
}
#endif
#ifdef LEAST_LATENCY_ALT
char* least_latency_alt(int* served_by_idx){
int r = rand() % servers_container->weight[3];
if (r < servers_container->weight[0]){
*served_by_idx = 0;
return servers_container->servers[0].ipaddress;
}
else if (r < servers_container->weight[1]){
*served_by_idx = 1;
return servers_container->servers[1].ipaddress;
}
else if (r < servers_container->weight[2]){
*served_by_idx = 2;
return servers_container->servers[2].ipaddress;
}
if (r < servers_container->weight[3]){
*served_by_idx = 3;
return servers_container->servers[3].ipaddress;
}
}
int init_server_container(AppServerContainer** container_ptr){
*container_ptr = (AppServerContainer*)malloc(sizeof(AppServerContainer));
(*container_ptr)->weight[0]=100;
(*container_ptr)->weight[1]=200;
(*container_ptr)->weight[2]=300;
(*container_ptr)->weight[3]=400;
(*container_ptr)->time[0]=100;
(*container_ptr)->time[1]=100;
(*container_ptr)->time[2]=100;
(*container_ptr)->time[3]=100;
init_server_struct(&((*container_ptr)->servers[0]), S2ELAB_IP);
init_server_struct(&((*container_ptr)->servers[1]), S2ELABSTUDENT_IP);
init_server_struct(&((*container_ptr)->servers[2]), S2ELABTEACHER_IP);
init_server_struct(&((*container_ptr)->servers[3]), S2ELABTUTOR_IP);
return 0;
}
/*
size_t ignore_response(char* ptr, size_t size, size_t nmemb, void* userdata){
// override default libcurl behavior and do not print output to stdout
return size*nmemb;
}
int perform_dummy_request(char* ipaddr){
CURL *curl;
CURLcode res;
char response_str[5000];
curl = curl_easy_init();
clock_t t;
printf("Performing dummy request on %s\n", ipaddr);
if (curl) {
curl_easy_setopt(curl, CURLOPT_URL, ipaddr);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, ignore_response);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void*)response_str);
t = clock();
res = curl_easy_perform(curl);
t = clock() - t;
if (res != CURLE_OK) {
fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
}
curl_easy_cleanup(curl);
return t;
}
}
*/
void weight_calculator(int idx, clock_t time){
int i;
float temp_weights[4], total_weight;
clock_t tmp_t, t[4], total_t;
printf("will update index %d with time %d\n", idx, (int)time);
// while(1){
total_t = 0;
total_weight = 0.0;
// for(i=0; i<4; i++){
// char ping_cmd[64];
// sprintf(ping_cmd, "ping -c 1 %s | tail -1 | awk -F '/' '{print $5}'", servers_container->servers[i].ipaddress);
// sprintf(ping_cmd, "curl --silent -o /dev/null %s -w %%{time_total}\\n", servers_container->servers[i].ipaddress);
// FILE *ping = popen(ping_cmd, "r");
// char res[8];
// fgets(res, sizeof(res), ping);
time = ((int)time + servers_container->time[idx]) / 2;
if (time<100){
time = 100;
}
else if (time>10000){
time = 10000;
}
servers_container->time[idx] = time;
printf("finally will update index %d with time %d\n", idx, (int)(servers_container->time[idx]));
// pclose(ping);
// printf("time passed: %d\n", (int)t[i]);
// total_t += t[i];
total_t = servers_container->time[0] + servers_container->time[1] + servers_container->time[2] + servers_container->time[3];
// }
// printf("total time: %d\n", (int)total_t);
servers_container->weight[0] = round(100*((float)((float)total_t/(float)servers_container->time[0])));
for(i=1; i<4; i++){
servers_container->weight[i] = round(100*((float)((float)total_t/(float)servers_container->time[i]))) + servers_container->weight[i-1];
// total_weight += temp_weights[i];
}
// printf("Servers tmp_weights: %f %f %f %f, total weight is %f\n", temp_weights[0], temp_weights[1], temp_weights[2], temp_weights[3], total_weight);
printf("Servers weights: %d %d %d %d\n", servers_container->weight[0], servers_container->weight[1], servers_container->weight[2], servers_container->weight[3]);
// pthread_mutex_unlock(&lb_state_mutex);
// sleep(SEC_INTERVAL);
// }
}
#endif
int destroy_server_container(AppServerContainer** servers_ptr){
free(*servers_ptr);
return 0;
}
int init_server_struct(AppServer* server, char* ip){
strcpy(server->ipaddress, ip);
return 0;
}
char* choose_and_fetch_ip(int* served_by_idx){
#ifdef ROUND_ROBIN
return round_robin();
#endif
#ifdef LEAST_CONN
return least_conn(served_by_idx);
#endif
#ifdef LEAST_LATENCY
return least_latency(served_by_idx);
#endif
#ifdef LEAST_LATENCY_ALT
return least_latency_alt(served_by_idx);
#endif
}
char* pretty_print_method(char* lb_method_identifier){
if (strcmp(lb_method_identifier, ROUND_ROBIN_ID)==0){
return "round robin";
}
else if (strcmp(lb_method_identifier, LEAST_CONN_ID)==0){
return "least_connections";
}
else if (strcmp(lb_method_identifier, LEAST_LATENCY_ID)==0){
return "least latency";
}
else if (strcmp(lb_method_identifier, LEAST_LATENCY_ALT_ID)==0){
return "improved least latency";
}
}