From 38652c3276645be9a798962e0643195ee98106be Mon Sep 17 00:00:00 2001
From: sitao <sitaowang1998@outlook.com>
Date: Fri, 28 Mar 2025 00:16:03 -0400
Subject: [PATCH] Fix fetch task logic

---
 src/spider/scheduler/FifoPolicy.cpp | 19 ++++++++++++++-----
 src/spider/scheduler/FifoPolicy.hpp |  2 ++
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/src/spider/scheduler/FifoPolicy.cpp b/src/spider/scheduler/FifoPolicy.cpp
index ae57dd60a..f1fc33123 100644
--- a/src/spider/scheduler/FifoPolicy.cpp
+++ b/src/spider/scheduler/FifoPolicy.cpp
@@ -1,6 +1,7 @@
 #include "FifoPolicy.hpp"
 
 #include <algorithm>
+#include <cstddef>
 #include <iterator>
 #include <memory>
 #include <optional>
@@ -29,12 +30,20 @@ auto FifoPolicy::schedule_next(
         boost::uuids::uuid const /*worker_id*/,
         std::string const& worker_addr
 ) -> std::optional<boost::uuids::uuid> {
-    if (m_tasks.empty()) {
-        fetch_tasks();
-        if (m_tasks.empty()) {
-            return std::nullopt;
-        }
+    std::optional<boost::uuids::uuid> const next_task = pop_next_task(worker_addr);
+    if (next_task.has_value()) {
+        return next_task;
     }
+    size_t const num_tasks = m_tasks.size();
+    fetch_tasks();
+    if (m_tasks.size() == num_tasks) {
+        return std::nullopt;
+    }
+    return pop_next_task(worker_addr);
+}
+
+auto FifoPolicy::pop_next_task(std::string const& worker_addr
+) -> std::optional<boost::uuids::uuid> {
     auto const reverse_begin = std::reverse_iterator(m_tasks.end());
     auto const reverse_end = std::reverse_iterator(m_tasks.begin());
     auto const it
diff --git a/src/spider/scheduler/FifoPolicy.hpp b/src/spider/scheduler/FifoPolicy.hpp
index 2c142f1f6..b62592460 100644
--- a/src/spider/scheduler/FifoPolicy.hpp
+++ b/src/spider/scheduler/FifoPolicy.hpp
@@ -30,6 +30,8 @@ class FifoPolicy final : public SchedulerPolicy {
 private:
     auto fetch_tasks() -> void;
 
+    auto pop_next_task(std::string const& worker_addr) -> std::optional<boost::uuids::uuid>;
+
     std::shared_ptr<core::MetadataStorage> m_metadata_store;
     std::shared_ptr<core::DataStorage> m_data_store;
     std::shared_ptr<core::StorageConnection> m_conn;