vcs-svn: implement perfect hash for top-level keys

Instead of interning property names and comparing their string_pool
keys, look them up in a table by string length, which should be about
as fast.

Another small step towards removing dependence on string_pool
altogether.

Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

diff --git a/vcs-svn/svndump.c b/vcs-svn/svndump.c
index 322d1cd305868c5d4eef910b729aeaeeab899b01..77680a31e8fed797715bc7c6727082574951ad0c 100644 (file)
--- a/vcs-svn/svndump.c
+++ b/vcs-svn/svndump.c
@@ -63,14 +63,6 @@ static struct {
        uint32_t version, uuid, url;
 } dump_ctx;
 
-static struct {
-       uint32_t uuid, revision_number, node_path, node_kind, node_action,
-               node_copyfrom_path, node_copyfrom_rev, text_content_length,
-               prop_content_length, content_length, svn_fs_dump_format_version,
-               /* version 3 format */
-               text_delta, prop_delta;
-} keys;
-
 static void reset_node_ctx(char *fname)
 {
        node_ctx.type = 0;
@@ -99,24 +91,6 @@ static void reset_dump_ctx(uint32_t url)
        dump_ctx.uuid = ~0;
 }
 
-static void init_keys(void)
-{
-       keys.uuid = pool_intern("UUID");
-       keys.revision_number = pool_intern("Revision-number");
-       keys.node_path = pool_intern("Node-path");
-       keys.node_kind = pool_intern("Node-kind");
-       keys.node_action = pool_intern("Node-action");
-       keys.node_copyfrom_path = pool_intern("Node-copyfrom-path");
-       keys.node_copyfrom_rev = pool_intern("Node-copyfrom-rev");
-       keys.text_content_length = pool_intern("Text-content-length");
-       keys.prop_content_length = pool_intern("Prop-content-length");
-       keys.content_length = pool_intern("Content-length");
-       keys.svn_fs_dump_format_version = pool_intern("SVN-fs-dump-format-version");
-       /* version 3 format (Subversion 1.1.0) */
-       keys.text_delta = pool_intern("Text-delta");
-       keys.prop_delta = pool_intern("Prop-delta");
-}
-
 static void handle_property(const struct strbuf *key_buf,
                                const char *val, uint32_t len,
                                uint32_t *type_set)
@@ -320,44 +294,61 @@ void svndump_read(const char *url)
        char *t;
        uint32_t active_ctx = DUMP_CTX;
        uint32_t len;
-       uint32_t key;
 
        reset_dump_ctx(pool_intern(url));
        while ((t = buffer_read_line(&input))) {
                val = strstr(t, ": ");
                if (!val)
                        continue;
-               *val++ = '\0';
-               *val++ = '\0';
-               key = pool_intern(t);
+               val += 2;
 
-               if (key == keys.svn_fs_dump_format_version) {
+               /* strlen(key) + 1 */
+               switch (val - t - 1) {
+               case sizeof("SVN-fs-dump-format-version"):
+                       if (constcmp(t, "SVN-fs-dump-format-version"))
+                               continue;
                        dump_ctx.version = atoi(val);
                        if (dump_ctx.version > 3)
                                die("expected svn dump format version <= 3, found %"PRIu32,
                                    dump_ctx.version);
-               } else if (key == keys.uuid) {
+                       break;
+               case sizeof("UUID"):
+                       if (constcmp(t, "UUID"))
+                               continue;
                        dump_ctx.uuid = pool_intern(val);
-               } else if (key == keys.revision_number) {
+                       break;
+               case sizeof("Revision-number"):
+                       if (constcmp(t, "Revision-number"))
+                               continue;
                        if (active_ctx == NODE_CTX)
                                handle_node();
                        if (active_ctx != DUMP_CTX)
                                handle_revision();
                        active_ctx = REV_CTX;
                        reset_rev_ctx(atoi(val));
-               } else if (key == keys.node_path) {
-                       if (active_ctx == NODE_CTX)
-                               handle_node();
-                       active_ctx = NODE_CTX;
-                       reset_node_ctx(val);
-               } else if (key == keys.node_kind) {
+                       break;
+               case sizeof("Node-path"):
+                       if (prefixcmp(t, "Node-"))
+                               continue;
+                       if (!constcmp(t + strlen("Node-"), "path")) {
+                               if (active_ctx == NODE_CTX)
+                                       handle_node();
+                               active_ctx = NODE_CTX;
+                               reset_node_ctx(val);
+                               break;
+                       }
+                       if (constcmp(t + strlen("Node-"), "kind"))
+                               continue;
                        if (!strcmp(val, "dir"))
                                node_ctx.type = REPO_MODE_DIR;
                        else if (!strcmp(val, "file"))
                                node_ctx.type = REPO_MODE_BLB;
                        else
                                fprintf(stderr, "Unknown node-kind: %s\n", val);
-               } else if (key == keys.node_action) {
+                       break;
+               case sizeof("Node-action"):
+                       if (constcmp(t, "Node-action"))
+                               continue;
                        if (!strcmp(val, "delete")) {
                                node_ctx.action = NODEACT_DELETE;
                        } else if (!strcmp(val, "add")) {
@@ -370,19 +361,38 @@ void svndump_read(const char *url)
                                fprintf(stderr, "Unknown node-action: %s\n", val);
                                node_ctx.action = NODEACT_UNKNOWN;
                        }
-               } else if (key == keys.node_copyfrom_path) {
+                       break;
+               case sizeof("Node-copyfrom-path"):
+                       if (constcmp(t, "Node-copyfrom-path"))
+                               continue;
                        pool_tok_seq(REPO_MAX_PATH_DEPTH, node_ctx.src, "/", val);
-               } else if (key == keys.node_copyfrom_rev) {
+                       break;
+               case sizeof("Node-copyfrom-rev"):
+                       if (constcmp(t, "Node-copyfrom-rev"))
+                               continue;
                        node_ctx.srcRev = atoi(val);
-               } else if (key == keys.text_content_length) {
-                       node_ctx.textLength = atoi(val);
-               } else if (key == keys.prop_content_length) {
+                       break;
+               case sizeof("Text-content-length"):
+                       if (!constcmp(t, "Text-content-length")) {
+                               node_ctx.textLength = atoi(val);
+                               break;
+                       }
+                       if (constcmp(t, "Prop-content-length"))
+                               continue;
                        node_ctx.propLength = atoi(val);
-               } else if (key == keys.text_delta) {
-                       node_ctx.text_delta = !strcmp(val, "true");
-               } else if (key == keys.prop_delta) {
+                       break;
+               case sizeof("Text-delta"):
+                       if (!constcmp(t, "Text-delta")) {
+                               node_ctx.text_delta = !strcmp(val, "true");
+                               break;
+                       }
+                       if (constcmp(t, "Prop-delta"))
+                               continue;
                        node_ctx.prop_delta = !strcmp(val, "true");
-               } else if (key == keys.content_length) {
+                       break;
+               case sizeof("Content-length"):
+                       if (constcmp(t, "Content-length"))
+                               continue;
                        len = atoi(val);
                        t = buffer_read_line(&input);
                        if (!t)
@@ -417,7 +427,6 @@ int svndump_init(const char *filename)
        reset_dump_ctx(~0);
        reset_rev_ctx(0);
        reset_node_ctx(NULL);
-       init_keys();
        return 0;
 }