follow empiredan advice

Author: 鲁鹏帆

src/replica/duplication/load_from_private_log.cpp

@@ -158,11 +158,11 @@ void load_from_private_log::find_log_file_to_start()
     // is cleared once WAL replay finished. They are unable to read.
     mutation_log::log_file_map_by_index new_file_map;
 
-    decree cleanable_decree = _private_log->get_cleanable_decree();
-    decree max_decree_gpid = _private_log->max_decree(get_gpid());
+    const auto decree cleanable_decree = _private_log->get_cleanable_decree();
+    const auto decree max_decree_gpid = _private_log->max_decree(get_gpid());
 
     if (max_decree_gpid <= cleanable_decree) {
-        LOG_ERROR_PREFIX("plog_file all error: max_decree_gpid {} , cleanable_decree {}",
+        LOG_ERROR_PREFIX("max_decree_gpid({}) should be > cleanable_decree({}) for plog",
                          max_decree_gpid,
                          cleanable_decree);
         return;
@@ -178,12 +178,9 @@ void load_from_private_log::find_log_file_to_start()
 
         new_file_map.emplace(it->first, file);
 
-        // next file map may can not open
-        gpid pid = get_gpid();
-        decree previous_log_max_decree = file->previous_log_max_decree(pid);
-        // these plog_file has possible be deleted do not open_read next plog_file , otherwise it
-        // may coredump
-        if (previous_log_max_decree <= cleanable_decree) {
+        // If the max decree of a log file falls within `cleanable_decree`, the file may be deleted
+        // during the GC of plog files. Therefore, these files should be skipped here.
+        if (cleanable_decree >= file->previous_log_max_decree(get_gpid())) {
             break;
         }
     }

src/replica/mutation_log.h

@@ -47,6 +47,7 @@
 #include "task/task_code.h"
 #include "task/task_tracker.h"
 #include "utils/autoref_ptr.h"
+#include "utils/ports.h"
 #include "utils/error_code.h"
 #include "utils/errors.h"
 #include "utils/zlocks.h"
@@ -404,7 +405,10 @@ class mutation_log : public ref_counter
     // be less than _plog_max_decree_on_disk.
     decree _plog_max_commit_on_disk;
 
-    decree _cleanable_decree; // for gc crush
+    // The decree threshold for private log garbage collection. Mutations with decree <= this
+    // value are considered cleanable and their log files may be deleted by GC.
+    // Protected by _lock in get/set.
+    decree _cleanable_decree;
 };
 
 using mutation_log_ptr = dsn::ref_ptr<mutation_log>;
@@ -425,18 +429,12 @@ class mutation_log_private : public mutation_log, private replica_base
         _tracker.cancel_outstanding_tasks();
     }
 
-    // Non-copyable and non-movable
-    mutation_log_private(const mutation_log_private &) = delete;
-    mutation_log_private &operator=(const mutation_log_private &) = delete;
-    mutation_log_private(mutation_log_private &&) = delete;
-    mutation_log_private &operator=(mutation_log_private &&) = delete;
-
     ::dsn::task_ptr append(mutation_ptr &mu,
                            dsn::task_code callback_code,
                            dsn::task_tracker *tracker,
                            aio_handler &&callback,
-                           int hash,
-                           int64_t *pending_size) override;
+                           int hash = 0,
+                           int64_t *pending_size = nullptr) override;
 
     bool get_learn_state_in_memory(decree start_decree, binary_writer &writer) const override;
 
@@ -449,6 +447,9 @@ class mutation_log_private : public mutation_log, private replica_base
     void flush_once() override;
 
 private:
+    DISALLOW_COPY_AND_ASSIGN(mutation_log_private);
+    DISALLOW_MOVE_AND_ASSIGN(mutation_log_private);
+
     // async write pending mutations into log file
     // Preconditions:
     // - _pending_write != nullptr