clear disk-cache between invocations and limit it to 128MB

Author: refset

src/clj/xt_play/config.clj

@@ -4,5 +4,6 @@
 
 (def node-config
   {:server {:port pgwire-port}
-   :disk-cache {:path "/tmp/xtdb-cache"}
+   :disk-cache {:path "/tmp/xtdb-cache"
+                :max-size-bytes (* 128 1024 1024)} ; 128MB - limit for Lambda
    :compactor {:threads 0}})

src/clj/xt_play/lambda.clj

@@ -5,14 +5,30 @@
   (:require [muuntaja.core :as m]
             [clojure.java.io :as io]
             [clojure.string :as str]
+            [clojure.tools.logging :as log]
             [xtdb.api :as xt]
             [xtdb.node :as xtn]
             [xt-play.config :as config]
             [xt-play.base64 :as b64]
             [xt-play.handler :as h]))
 
+(defn- clear-directory
+  "Recursively delete all contents of a directory"
+  [^java.io.File dir]
+  (when (.exists dir)
+    (doseq [file (.listFiles dir)]
+      (if (.isDirectory file)
+        (do
+          (clear-directory file)
+          (.delete file))
+        (.delete file)))
+    (log/info "Cleared disk cache directory:" (.getPath dir))))
+
 (defn -init []
-  ; NOTE: This ensure xtdb is warmed up before starting the server
+  ; Clear disk cache from previous Lambda container executions
+  (clear-directory (io/file "/tmp/xtdb-cache"))
+
+  ; NOTE: This ensures xtdb is warmed up before starting the server
   ;       Otherwise, the first few requests will time out
   (with-open [node (xtn/start-node config/node-config)]
     (xt/status node))

src/clj/xt_play/xtdb.clj

@@ -1,12 +1,31 @@
 (ns xt-play.xtdb
   (:require [clojure.tools.logging :as log]
+            [clojure.java.io :as io]
             [next.jdbc :as jdbc]
             [xt-play.config :as config]
             [xtdb.api :as xt]
             [xtdb.node :as xtn]
             [xtdb.next.jdbc :as xjdbc]))
 
+(defn- clear-cache-directory
+  "Clear disk cache before starting a new node to prevent /tmp exhaustion"
+  []
+  (let [cache-dir (io/file "/tmp/xtdb-cache")]
+    (when (.exists cache-dir)
+      (doseq [file (.listFiles cache-dir)]
+        (if (.isDirectory file)
+          (do
+            (doseq [f (.listFiles file)]
+              (.delete f))
+            (.delete file))
+          (.delete file)))
+      (log/debug "Cleared disk cache directory before node start"))))
+
 (defn with-xtdb [f]
+  ;; Clear cache before each request to prevent /tmp exhaustion
+  ;; This is critical for Lambda with limited ephemeral storage
+  (clear-cache-directory)
+
   (with-open [node (xtn/start-node config/node-config)]
     (f node)))