cspcl/pool.patch at main · DTN-MTP/cspcl · GitHub

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diff --git a/src/cspcl.c b/src/cspcl.c
index 1603696..9dd426e 100644
--- a/src/cspcl.c
+++ b/src/cspcl.c
@@ -12,6 +12,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>

 /* CSP library headers */
 #include <csp/arch/csp_malloc.h>
@@ -47,10 +48,19 @@ static int cspcl_pool_unlock(cspcl_conn_pool_t *pool) {
 #endif
 }

+static uint64_t cspcl_now_ms(void) {
+  struct timespec ts;
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  return (uint64_t)ts.tv_sec * 1000ULL + (uint64_t)ts.tv_nsec / 1000000ULL;
+}
+
 static csp_conn_t *cspcl_pool_get_or_create_locked(cspcl_conn_pool_t *pool,
                                                    uint8_t dest_addr,
                                                    uint8_t dest_port) {
+  uint64_t now = cspcl_now_ms();
   size_t free_slot = CSPCL_CONN_POOL_SIZE;
+  size_t lru_idx = 0;
+  uint64_t lru_time = UINT64_MAX;

   for (size_t i = 0; i < CSPCL_CONN_POOL_SIZE; i++) {
     if (!pool->entries[i].used) {
@@ -63,8 +73,14 @@ static csp_conn_t *cspcl_pool_get_or_create_locked(cspcl_conn_pool_t *pool,
     if (pool->entries[i].dest_addr == dest_addr &&
         pool->entries[i].dest_port == dest_port &&
         pool->entries[i].conn != NULL) {
+      pool->entries[i].last_used_ms = now;
       return pool->entries[i].conn;
     }
+
+    if (pool->entries[i].last_used_ms < lru_time) {
+      lru_time = pool->entries[i].last_used_ms;
+      lru_idx = i;
+    }
   }

   csp_conn_t *conn = csp_connect(CSP_PRIO_NORM, dest_addr, dest_port,
@@ -74,7 +90,8 @@ static csp_conn_t *cspcl_pool_get_or_create_locked(cspcl_conn_pool_t *pool,
   }

   if (free_slot == CSPCL_CONN_POOL_SIZE) {
-    free_slot = 0;
+    /* No free slot found, evict LRU */
+    free_slot = lru_idx;
     if (pool->entries[free_slot].conn != NULL) {
       csp_close(pool->entries[free_slot].conn);
     }
@@ -84,6 +101,7 @@ static csp_conn_t *cspcl_pool_get_or_create_locked(cspcl_conn_pool_t *pool,
   pool->entries[free_slot].dest_addr = dest_addr;
   pool->entries[free_slot].dest_port = dest_port;
   pool->entries[free_slot].conn = conn;
+  pool->entries[free_slot].last_used_ms = now;

   return conn;
 }
@@ -102,6 +120,7 @@ static void cspcl_pool_invalidate_locked(cspcl_conn_pool_t *pool,
       }
       pool->entries[i].conn = NULL;
       pool->entries[i].used = false;
+      pool->entries[i].last_used_ms = 0;
       return;
     }
   }
@@ -255,6 +274,7 @@ void cspcl_conn_pool_cleanup(cspcl_conn_pool_t *pool) {
     }
     pool->entries[i].used = false;
     pool->entries[i].conn = NULL;
+    pool->entries[i].last_used_ms = 0;
   }

   (void)cspcl_pool_unlock(pool);
diff --git a/src/cspcl.h b/src/cspcl.h
index 66ced25..0290768 100644
--- a/src/cspcl.h
+++ b/src/cspcl.h
@@ -104,6 +104,7 @@ typedef struct {
   uint8_t dest_addr;
   uint8_t dest_port;
   csp_conn_t *conn;
+  uint64_t last_used_ms; /* Monotonic ms timestamp for LRU eviction */
 } cspcl_conn_pool_entry_t;

 typedef struct {