Add GetAllSnapshots functionality to SnapshotList (#1240)

CMakeLists.txt

@@ -330,6 +330,7 @@ if(LEVELDB_BUILD_TESTS)
         "db/autocompact_test.cc"
         "db/corruption_test.cc"
         "db/db_test.cc"
+        "db/snapshot_test.cc"
         "db/dbformat_test.cc"
         "db/filename_test.cc"
         "db/log_test.cc"

db/db_impl.cc

@@ -1575,4 +1575,12 @@ Status DestroyDB(const std::string& dbname, const Options& options) {
   return result;
 }
 
+std::vector<const Snapshot*> DBImpl::GetAllSnapshots() {
+  std::vector<const Snapshot*> snapshots;
+  mutex_.Lock();
+  snapshots = snapshots_.GetAllSnapshots();  // Call the SnapshotList method
+  mutex_.Unlock();
+  return snapshots;
+}
+
 }  // namespace leveldb

db/db_impl.h

@@ -9,6 +9,7 @@
 #include <deque>
 #include <set>
 #include <string>
+#include <vector> 
 
 #include "db/dbformat.h"
 #include "db/log_writer.h"
@@ -48,6 +49,9 @@ class DBImpl : public DB {
   bool GetProperty(const Slice& property, std::string* value) override;
   void GetApproximateSizes(const Range* range, int n, uint64_t* sizes) override;
   void CompactRange(const Slice* begin, const Slice* end) override;
+ 
+  // Retrieve all active snapshots in the database
+  std::vector<const Snapshot*> GetAllSnapshots() override;
 
   // Extra methods (for testing) that are not in the public DB interface
 

db/snapshot.h

@@ -85,6 +85,17 @@ class SnapshotList {
     delete snapshot;
   }
 
+  // Retrieves all snapshots in the list.
+  //
+  // This method iterates through the linked list and collects all snapshots.
+  std::vector<const Snapshot*> GetAllSnapshots() const {
+    std::vector<const Snapshot*> snapshots;
+    for (const SnapshotImpl* s = head_.next_; s != &head_; s = s->next_) {
+      snapshots.push_back(static_cast<const Snapshot*>(s));
+    }
+    return snapshots;
+  }
+
  private:
   // Dummy head of doubly-linked list of snapshots
   SnapshotImpl head_;

db/snapshot_test.cc

@@ -0,0 +1,30 @@
+#include "db/db_impl.h"
+#include "gtest/gtest.h"
+
+namespace leveldb {
+
+// Test to validate GetAllSnapshots retrieves all snapshots correctly.
+TEST(SnapshotTest, GetAllSnapshots) {
+  SnapshotList snapshot_list;
+
+  // Create some snapshots
+  SnapshotImpl* s1 = snapshot_list.New(1);
+  SnapshotImpl* s2 = snapshot_list.New(2);
+  SnapshotImpl* s3 = snapshot_list.New(3);
+
+  // Use GetAllSnapshots to retrieve them
+  std::vector<const Snapshot*> snapshots = snapshot_list.GetAllSnapshots();
+
+  // Validate the results
+  ASSERT_EQ(snapshots.size(), 3);
+  EXPECT_EQ(static_cast<const SnapshotImpl*>(snapshots[0])->sequence_number(), 1);
+  EXPECT_EQ(static_cast<const SnapshotImpl*>(snapshots[1])->sequence_number(), 2);
+  EXPECT_EQ(static_cast<const SnapshotImpl*>(snapshots[2])->sequence_number(), 3);
+
+  // Clean up
+  snapshot_list.Delete(s1);
+  snapshot_list.Delete(s2);
+  snapshot_list.Delete(s3);
+}
+
+}  

include/leveldb/db.h

@@ -145,6 +145,9 @@ class LEVELDB_EXPORT DB {
   // Therefore the following call will compact the entire database:
   //    db->CompactRange(nullptr, nullptr);
   virtual void CompactRange(const Slice* begin, const Slice* end) = 0;
+
+  // Retrieve all active snapshots in the database.
+  virtual std::vector<const Snapshot*> GetAllSnapshots() = 0;
 };
 
 // Destroy the contents of the specified database.