esp_http_server/lru_counter_for_timestamp:Added LRU counter for timer

Replaced the os timer in http server by LRU counter. The timestamp is
unnecessary for LRU.

components/esp_http_server/include/esp_http_server.h

@@ -623,7 +623,7 @@ esp_err_t httpd_sess_set_pending_override(httpd_handle_t hd, int sockfd, httpd_p
  * session socket fd, from within a URI handler, ie. :
  *      httpd_sess_get_ctx(),
  *      httpd_sess_trigger_close(),
- *      httpd_sess_update_timestamp().
+ *      httpd_sess_update_lru_counter().
  *
  * @note    This API is supposed to be called only from the context of
  *          a URI handler where httpd_req_t* request pointer is valid.
@@ -1215,15 +1215,15 @@ void *httpd_get_global_transport_ctx(httpd_handle_t handle);
 esp_err_t httpd_sess_trigger_close(httpd_handle_t handle, int sockfd);
 
 /**
- * @brief   Update timestamp for a given socket
+ * @brief   Update LRU counter for a given socket
  *
- * Timestamps are internally associated with each session to monitor
+ * LRU Counters are internally associated with each session to monitor
  * how recently a session exchanged traffic. When LRU purge is enabled,
  * if a client is requesting for connection but maximum number of
  * sockets/sessions is reached, then the session having the earliest
- * timestamp is closed automatically.
+ * LRU counter is closed automatically.
  *
- * Updating the timestamp manually prevents the socket from being purged
+ * Updating the LRU counter manually prevents the socket from being purged
  * due to the Least Recently Used (LRU) logic, even though it might not
  * have received traffic for some time. This is useful when all open
  * sockets/session are frequently exchanging traffic but the user specifically
@@ -1234,15 +1234,15 @@ esp_err_t httpd_sess_trigger_close(httpd_handle_t handle, int sockfd);
  *          is enabled.
  *
  * @param[in] handle    Handle to server returned by httpd_start
- * @param[in] sockfd    The socket descriptor of the session for which timestamp
+ * @param[in] sockfd    The socket descriptor of the session for which LRU counter
  *                      is to be updated
  *
  * @return
- *  - ESP_OK : Socket found and timestamp updated
+ *  - ESP_OK : Socket found and LRU counter updated
  *  - ESP_ERR_NOT_FOUND   : Socket not found
  *  - ESP_ERR_INVALID_ARG : Null arguments
  */
-esp_err_t httpd_sess_update_timestamp(httpd_handle_t handle, int sockfd);
+esp_err_t httpd_sess_update_lru_counter(httpd_handle_t handle, int sockfd);
 
 /** End of Session
  * @}

components/esp_http_server/src/esp_httpd_priv.h

@@ -125,7 +125,7 @@ struct sock_db {
     httpd_send_func_t send_fn;              /*!< Send function for this socket */
     httpd_recv_func_t recv_fn;              /*!< Receive function for this socket */
     httpd_pending_func_t pending_fn;        /*!< Pending function for this socket */
-    int64_t timestamp;                      /*!< Timestamp indicating when the socket was last used */
+    uint64_t lru_counter;                   /*!< LRU Counter indicating when the socket was last used */
     char pending_data[PARSER_BLOCK_SIZE];   /*!< Buffer for pending data to be received */
     size_t pending_len;                     /*!< Length of pending data to be received */
 };

components/esp_http_server/src/httpd_sess.c

@@ -195,6 +195,12 @@ static int fd_is_valid(int fd)
     return fcntl(fd, F_GETFD) != -1 || errno != EBADF;
 }
 
+static inline uint64_t httpd_sess_get_lru_counter()
+{
+    static uint64_t lru_counter = 0;
+    return lru_counter++;
+}
+
 void httpd_sess_delete_invalid(struct httpd_data *hd)
 {
     for (int i = 0; i < hd->config.max_open_sockets; i++) {
@@ -297,11 +303,11 @@ esp_err_t httpd_sess_process(struct httpd_data *hd, int newfd)
         return ESP_FAIL;
     }
     ESP_LOGD(TAG, LOG_FMT("success"));
-    sd->timestamp = httpd_os_get_timestamp();
+    sd->lru_counter = httpd_sess_get_lru_counter();
     return ESP_OK;
 }
 
-esp_err_t httpd_sess_update_timestamp(httpd_handle_t handle, int sockfd)
+esp_err_t httpd_sess_update_lru_counter(httpd_handle_t handle, int sockfd)
 {
     if (handle == NULL) {
         return ESP_ERR_INVALID_ARG;
@@ -312,7 +318,7 @@ esp_err_t httpd_sess_update_timestamp(httpd_handle_t handle, int sockfd)
     int i;
     for (i = 0; i < hd->config.max_open_sockets; i++) {
         if (hd->hd_sd[i].fd == sockfd) {
-            hd->hd_sd[i].timestamp = httpd_os_get_timestamp();
+            hd->hd_sd[i].lru_counter = httpd_sess_get_lru_counter();
             return ESP_OK;
         }
     }
@@ -321,7 +327,7 @@ esp_err_t httpd_sess_update_timestamp(httpd_handle_t handle, int sockfd)
 
 esp_err_t httpd_sess_close_lru(struct httpd_data *hd)
 {
-    int64_t timestamp = INT64_MAX;
+    uint64_t lru_counter = UINT64_MAX;
     int lru_fd = -1;
     int i;
     for (i = 0; i < hd->config.max_open_sockets; i++) {
@@ -332,8 +338,8 @@ esp_err_t httpd_sess_close_lru(struct httpd_data *hd)
         if (hd->hd_sd[i].fd == -1) {
             return ESP_OK;
         }
-        if (hd->hd_sd[i].timestamp < timestamp) {
+        if (hd->hd_sd[i].lru_counter < lru_counter) {
-            timestamp = hd->hd_sd[i].timestamp;
+            lru_counter = hd->hd_sd[i].lru_counter;
             lru_fd = hd->hd_sd[i].fd;
         }
     }

components/esp_http_server/src/port/esp32/osal.h

@@ -52,11 +52,6 @@ static inline void httpd_os_thread_sleep(int msecs)
     vTaskDelay(msecs / portTICK_RATE_MS);
 }
 
-static inline int64_t httpd_os_get_timestamp()
-{
-    return esp_timer_get_time();
-}
-
 static inline othread_t httpd_os_thread_handle()
 {
     return xTaskGetCurrentTaskHandle();