From e91edf226b1f7e9b226f34f2fd4b46c7ab8e15f0 Mon Sep 17 00:00:00 2001
From: Michael Vrable <mvrable@cs.ucsd.edu>
Date: Mon, 31 Aug 2009 10:56:18 -0700
Subject: [PATCH] Start on a basic in-memory key/value store.

---
 Makefile  |  2 +-
 bluesky.h | 14 +++++++++++
 inode.c   | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 8a1ea81..54aedc9 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ CFLAGS=-O -std=gnu99 -Wall -D_FILE_OFFSET_BITS=64 $(DEBUG) \
 LDFLAGS=$(DEBUG) $(shell pkg-config --libs $(PACKAGES))
 SUBDIRS=nfs3
 
-SRCS=dir.c inode.c
+SRCS=dir.c inode.c store.c
 OBJS=$(SRCS:.c=.o)
 
 all : bluesky
diff --git a/bluesky.h b/bluesky.h
index b5f5ab5..5571db6 100644
--- a/bluesky.h
+++ b/bluesky.h
@@ -12,6 +12,19 @@
 #include <stdint.h>
 #include <glib.h>
 
+/* Reference-counted blocks of memory, used for passing data in and out of
+ * storage backends and in other places. */
+typedef struct {
+    gint refcount;
+    gpointer data;
+    gsize len;
+} BlueSkyRCStr;
+
+BlueSkyRCStr *bluesky_string_new(gpointer data, gsize len);
+void bluesky_string_ref(BlueSkyRCStr *string);
+void bluesky_string_unref(BlueSkyRCStr *string);
+BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string);
+
 /* File types.  The numeric values are chosen to match with those used in
  * NFSv3. */
 typedef enum {
@@ -120,6 +133,7 @@ gboolean bluesky_directory_insert(BlueSkyInode *dir, gchar *name,
 void bluesky_directory_dump(BlueSkyInode *dir);
 
 void bluesky_block_touch(BlueSkyInode *inode, uint64_t i);
+void bluesky_block_flush(BlueSkyBlock *block);
 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size);
 void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
                         const char *data, gint len);
diff --git a/inode.c b/inode.c
index 154614d..162e154 100644
--- a/inode.c
+++ b/inode.c
@@ -37,6 +37,54 @@ void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime)
         inode->mtime = now;
 }
 
+/* Compute the HMAC keyed-hash function using the given hash algorithm, data,
+ * and key. */
+void compute_hmac(GChecksumType algo,
+                  const guchar *data, gsize data_len,
+                  const guchar *key, gsize key_len,
+                  guint8 *buffer, gsize *digest_len)
+{
+    int block_size;
+
+    switch (algo) {
+    case G_CHECKSUM_MD5:
+    case G_CHECKSUM_SHA1:
+    case G_CHECKSUM_SHA256:
+        block_size = 64;
+        break;
+    default:
+        g_error("Unknown hash algorithm for HMAC: %d\n", algo);
+    }
+
+    gsize digest_size = g_checksum_type_get_length(algo);
+
+    guchar keybuf[block_size];
+    memset(keybuf, 0, block_size);
+    memcpy(keybuf, key, MIN(block_size, key_len));
+    for (int i = 0; i < block_size; i++)
+        keybuf[i] ^= 0x36;
+
+    GChecksum *csum1 = g_checksum_new(algo);
+    g_checksum_update(csum1, keybuf, block_size);
+    g_checksum_update(csum1, data, data_len);
+    guint8 digest[digest_size];
+    g_checksum_get_digest(csum1, digest, &digest_size);
+
+    memset(keybuf, 0, block_size);
+    memcpy(keybuf, key, MIN(block_size, key_len));
+    for (int i = 0; i < block_size; i++)
+        keybuf[i] ^= 0x5c;
+
+    GChecksum *csum2 = g_checksum_new(algo);
+    g_checksum_update(csum2, keybuf, block_size);
+    g_checksum_update(csum2, digest, digest_size);
+
+    g_checksum_get_digest(csum2, buffer, digest_len);
+
+    g_checksum_free(csum1);
+    g_checksum_free(csum2);
+}
+
 /* Unfortunately a glib hash table is only guaranteed to be able to store
  * 32-bit keys if we use the key directly.  If we want 64-bit inode numbers,
  * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
@@ -220,6 +268,7 @@ void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
         BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
                                          block_num);
         memcpy(&b->data[block_offset], data, bytes);
+        bluesky_block_flush(b);
 
         offset += bytes;
         data += bytes;
@@ -262,3 +311,27 @@ void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
         len -= bytes;
     }
 }
+
+/* Write the given block to cloud-backed storage and mark it clean. */
+void bluesky_block_flush(BlueSkyBlock *block)
+{
+    if (block->type != BLUESKY_BLOCK_DIRTY)
+        return;
+
+    BlueSkyRCStr *data = bluesky_string_new(g_memdup(block->data,
+                                                     BLUESKY_BLOCK_SIZE),
+                                            BLUESKY_BLOCK_SIZE);
+
+    GChecksum *csum = g_checksum_new(G_CHECKSUM_SHA256);
+    g_checksum_update(csum, data->data, data->len);
+    const gchar *name = g_checksum_get_string(csum);
+
+    g_print("Flushing block as %s\n", name);
+    //memstore_put(store, name, data);
+    g_free(block->ref);
+    block->ref = g_strdup(name);
+    block->type = BLUESKY_BLOCK_CACHED;
+
+    g_checksum_free(csum);
+    bluesky_string_unref(data);
+}
-- 
2.20.1