fix:prevent hang during process exit due to tmp file cleanup

lib/database/filedown.js

@@ -4,7 +4,6 @@ var async = require("async");
 var fs = require("fs");
 var path = require("path");
 var tmp = require("tmp");
-tmp.setGracefulCleanup();
 
 util.inherits(FileDown, AbstractLevelDOWN);
 
@@ -37,6 +36,34 @@ const accessQueue = {
   },
   cache: {}
 };
+
+const fds = new Set();
+const cleanup = (exit) => {
+  try {
+    fds.forEach((fdPath) => {
+      const [fd, path] = fdPath;
+      try {
+        fs.closeSync(fd);
+      } catch (e) {
+        // ignore
+      } finally {
+        try {
+          fs.unlinkSync(path);
+        } catch (e) {
+          // ignore
+        }
+      }
+    });
+    fds.clear();
+  } finally {
+    if (exit) {
+      process.exit(0);
+    }
+  }
+};
+process.on("SIGINT", cleanup);
+process.on("exit", () => cleanup(false));
+
 FileDown.prototype._put = function(key, value, options, callback) {
   const lKey = path.join(this.location, key);
   // This fixes an issue caused by writing AND reading the same key multiple times
@@ -52,46 +79,38 @@ FileDown.prototype._put = function(key, value, options, callback) {
   // leveldb implementation that doesn't use a separate file for every key Soon(TM).
   accessQueue.execute(lKey, () => {
     // get a tmp file to write the contents to...
-    tmp.file((err, path, fd, cleanupTmpFile) => {
+    tmp.file({ keep: true }, (err, path, fd, cleanupTmpFile) => {
       if (err) {
         callback(err);
         accessQueue.next(lKey);
         return;
       }
+      const pair = [fd, path];
+      fds.add(pair);
+      const cleanupAndCallback = (err) => {
+        err && cleanupTmpFile();
+        fds.delete(pair);
+        callback(err);
+        accessQueue.next(lKey);
+      };
 
       // write the value to our temporary file
       fs.writeFile(fd, value, "utf8", (err) => {
         if (err) {
-          cleanupTmpFile();
-          callback(err);
-          accessQueue.next(lKey);
+          cleanupAndCallback(err);
           return;
         }
 
         // It worked! Move the temporary file to its final destination
         fs.rename(path, lKey, (err) => {
           if (err) {
-            cleanupTmpFile();
-            callback(err);
-            accessQueue.next(lKey);
+            cleanupAndCallback(err);
             return;
           }
 
           // make sure we close this file descriptor now that the file is no
           // longer "temporary" (because we successfully moved it)
-          fs.close(fd, (err) => {
-            if (err) {
-              // at this point things seem to have worked, but juuuussttt in
-              // case `fs.close` fails, let's log some info so we can try to
-              // debug it
-              console.warn("An unexpected file descriptor close error occured: ", err);
-              cleanupTmpFile();
-            }
-            callback();
-
-            // if there is more work to be done on this key, do it.
-            accessQueue.next(lKey);
-          });
+          fs.close(fd, () => cleanupAndCallback());
         });
       });
     });