From 51859528c5de1c90c553d1f174869005711f162a Mon Sep 17 00:00:00 2001
From: Michael Vrable <mvrable@cs.ucsd.edu>
Date: Thu, 3 May 2007 15:56:04 -0700
Subject: [PATCH] Start work on a more object-oriented interface for creating
 objects.

---
 scandir.cc | 25 +++++++++++++++++++------
 store.cc   | 26 ++++++++++++++++++++++++++
 store.h    | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/scandir.cc b/scandir.cc
index f3bf302..223a99c 100644
--- a/scandir.cc
+++ b/scandir.cc
@@ -92,8 +92,12 @@ void dumpfile(int fd, dictionary &file_info, ostream &metadata)
         hash.process(block_buf, bytes);
 
         // tarstore processing
-        string blockid = tss->write_object(block_buf, bytes, "data");
-        segment_list.push_back(blockid);
+        LbsObject *o = new LbsObject;
+        o->set_group("data");
+        o->set_data(block_buf, bytes);
+        o->write(tss);
+        segment_list.push_back(o->get_name());
+        delete o;
 
         size += bytes;
     }
@@ -118,9 +122,13 @@ void dumpfile(int fd, dictionary &file_info, ostream &metadata)
              i != segment_list.end(); ++i) {
             blocklist += *i + "\n";
         }
-        string indirect = tss->write_object(blocklist.data(), blocklist.size(),
-                                            "indirect");
-        file_info["data"] = "@" + indirect;
+
+        LbsObject *i = new LbsObject;
+        i->set_group("indirect");
+        i->set_data(blocklist.data(), blocklist.size());
+        i->write(tss);
+        file_info["data"] = "@" + i->get_name();
+        delete i;
     }
 }
 
@@ -279,7 +287,12 @@ int main(int argc, char *argv[])
     }
 
     const string md = metadata.str();
-    string root = tss->write_object(md.data(), md.size(), "root");
+
+    LbsObject *r = new LbsObject;
+    r->set_group("root");
+    r->set_data(md.data(), md.size());
+    r->write(tss);
+    delete r;
 
     tss->sync();
     delete tss;
diff --git a/store.cc b/store.cc
index 00fd26c..804992f 100644
--- a/store.cc
+++ b/store.cc
@@ -6,6 +6,7 @@
  * is built on top of libtar, and represents segments as TAR files and objects
  * as files within them. */
 
+#include <assert.h>
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -183,3 +184,28 @@ string TarSegmentStore::object_reference_to_segment(const string &object)
 {
     return object;
 }
+
+LbsObject::LbsObject()
+    : group(""), data(NULL), data_len(0), written(false)
+{
+}
+
+LbsObject::~LbsObject()
+{
+}
+
+void LbsObject::add_reference(const LbsObject *o)
+{
+    // TODO: Implement
+}
+
+void LbsObject::write(TarSegmentStore *store)
+{
+    assert(data != NULL);
+    assert(!written);
+
+    name = store->write_object(data, data_len, group);
+
+    written = true;
+    data = NULL;
+}
diff --git a/store.h b/store.h
index 6acee7f..516a20c 100644
--- a/store.h
+++ b/store.h
@@ -21,6 +21,8 @@
 
 #include "sha1.h"
 
+class LbsObject;
+
 /* In memory datatype to represent key/value pairs of information, such as file
  * metadata.  Currently implemented as map<string, string>. */
 typedef std::map<std::string, std::string> dictionary;
@@ -101,4 +103,48 @@ private:
     std::string object_reference_to_segment(const std::string &object);
 };
 
+/* An in-memory representation of an object, which can be incrementally built
+ * before it is written out to a segment. */
+class LbsObject {
+public:
+    LbsObject();
+    ~LbsObject();
+
+    // If an object is placed in a group, it will be written out to segments
+    // only containing other objects in the same group.  A group name is simply
+    // a string.
+    //std::string get_group() const { return group; }
+    void set_group(const std::string &g) { group = g; }
+
+    // Data in an object must be written all at once, and cannot be generated
+    // incrementally.  Data can be an arbitrary block of binary data of any
+    // size.  The pointer to the data need only remain valid until write() is
+    // called.
+    //const char *get_data() const { return data; }
+    //size_t get_data_len() const { return data_len; }
+    void set_data(const char *d, size_t len) { data = d; data_len = len; }
+
+    // Write an object to a segment, thus making it permanent.  This function
+    // can be called at most once.
+    void write(TarSegmentStore *store);
+
+    // An object is assigned a permanent name once it has been written to a
+    // segment.  Until that time, its name cannot be determined.
+    std::string get_name() const { return name; }
+
+    // Logically, one object may reference other objects (such as a metadata
+    // listing referncing actual file data blocks).  Such references should be
+    // noted explicitly.  It may eventually be used to build up a tree of
+    // checksums for later verifying integrity.
+    void add_reference(const LbsObject *o);
+
+private:
+    std::string group;
+    const char *data;
+    size_t data_len;
+
+    bool written;
+    std::string name;
+};
+
 #endif // _LBS_TARSTORE_H
-- 
2.20.1