From 0c5ef6abcf1b59c62f99ab60f44c90c2e5ddd267 Mon Sep 17 00:00:00 2001
From: Aaryamann Challani <43716372+rymnc@users.noreply.github.com>
Date: Fri, 25 Aug 2023 05:34:20 +0530
Subject: [PATCH] fix(rln): use config.open instead of sled::open (#209)

fix: include tries & exp backoff to catch WouldBlock errors
---
 utils/src/pm_tree/sled_adapter.rs | 48 ++++++++++++++++++++++---------
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/utils/src/pm_tree/sled_adapter.rs b/utils/src/pm_tree/sled_adapter.rs
index 96dc16c..c35533f 100644
--- a/utils/src/pm_tree/sled_adapter.rs
+++ b/utils/src/pm_tree/sled_adapter.rs
@@ -2,29 +2,51 @@ use pmtree::*;
 
 use sled::Db as Sled;
 use std::collections::HashMap;
+use std::thread;
+use std::time::Duration;
 
 pub struct SledDB(Sled);
 
+impl SledDB {
+    fn new_with_tries(config: <SledDB as Database>::Config, tries: u32) -> PmtreeResult<Self> {
+        // If we've tried more than 10 times, we give up and return an error.
+        if tries >= 10 {
+            return Err(PmtreeErrorKind::DatabaseError(
+                DatabaseErrorKind::CustomError(format!(
+                    "Cannot create database: exceeded maximum retry attempts. {config:#?}"
+                )),
+            ));
+        }
+        match config.open() {
+            Ok(db) => Ok(SledDB(db)),
+            Err(e) if e.to_string().contains("WouldBlock") => {
+                // try till the fd is freed
+                // sleep for 10^tries milliseconds, then recursively try again
+                thread::sleep(Duration::from_millis(10u64.pow(tries)));
+                Self::new_with_tries(config, tries + 1)
+            }
+            Err(e) => {
+                // On any other error, we return immediately.
+                Err(PmtreeErrorKind::DatabaseError(
+                    DatabaseErrorKind::CustomError(format!(
+                        "Cannot create database: {e} {config:#?}"
+                    )),
+                ))
+            }
+        }
+    }
+}
+
 impl Database for SledDB {
     type Config = sled::Config;
 
     fn new(config: Self::Config) -> PmtreeResult<Self> {
-        let db: Sled = match config.open() {
-            Ok(db) => db,
-            Err(e) => {
-                return Err(PmtreeErrorKind::DatabaseError(
-                    DatabaseErrorKind::CustomError(format!(
-                        "Cannot create database: {e} {config:#?}",
-                    )),
-                ))
-            }
-        };
-
-        Ok(SledDB(db))
+        let db = Self::new_with_tries(config, 0)?;
+        Ok(db)
     }
 
     fn load(config: Self::Config) -> PmtreeResult<Self> {
-        let db: Sled = match sled::open(&config.path) {
+        let db = match config.open() {
             Ok(db) => db,
             Err(e) => {
                 return Err(PmtreeErrorKind::DatabaseError(