Add checksums to tarstore, and partially migrate to using it for storage.

[cumulus.git] / tarstore.h

diff --git a/tarstore.h b/tarstore.h
index 923c75a..009dd90 100644 (file)
--- a/tarstore.h
+++ b/tarstore.h
@@ -13,19 +13,55 @@
 #include <libtar.h>
 
 #include <string>
+#include <iostream>
+#include <sstream>
 
 #include "store.h"
 
+/* A simple wrapper around a single TAR file to represent a segment.  Objects
+ * may only be written out all at once, since the tar header must be written
+ * first; incremental writing is not supported. */
 class Tarfile {
 public:
     Tarfile(const std::string &path, const std::string &segment);
-    virtual ~Tarfile();
+    ~Tarfile();
 
     void write_object(int id, const char *data, size_t len);
 
 private:
+    void internal_write_object(const std::string &path,
+                               const char *data, size_t len);
+
     std::string segment_name;
+    std::ostringstream checksums;
     TAR *t;
 };
 
+class TarSegmentStore {
+public:
+    // New segments will be stored in the given directory.
+    TarSegmentStore(const std::string &path) { this->path = path; }
+    ~TarSegmentStore() { sync(); }
+
+    // Writes an object to segment in the store, and returns the name
+    // (segment/object) to refer to it.  The optional parameter group can be
+    // used to control object placement; objects with different group
+    // parameters are kept in separate segments.
+    std::string write_object(const char *data, size_t len,
+                             const std::string &group = "");
+
+    // Ensure all segments have been fully written.
+    void sync();
+
+private:
+    struct segment_info {
+        Tarfile *file;
+        std::string name;       // UUID
+        int count;              // Objects written to this segment
+    };
+
+    std::string path;
+    std::map<std::string, struct segment_info *> segments;
+};
+
 #endif // _LBS_TARSTORE_H