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![Jeff King](/assets/img/avatar_default.png)
It is not unreasonable to ask cat-file for a batch-check format of simply "%(objectname)". At first glance this seems like a noop (you are generally already feeding the object names on stdin!), but it has a few uses: 1. With --batch-all-objects, you can generate a listing of the sha1s present in the repository, without any input. 2. You do not have to feed sha1s; you can feed arbitrary sha1 expressions and have git resolve them en masse. 3. You can even feed a raw sha1, with the result that git will tell you whether we actually have the object or not. In case 3, the call to sha1_object_info is useful; it tells us whether the object exists or not (technically we could swap this out for has_sha1_file, but the cost is roughly the same). In case 2, the existence check is of debatable value. A mass-resolution might prefer performance to safety (against outputting a value for a corrupted ref, for example). However, the object lookup cost is likely not as noticeable compared to the resolution cost. And since we have provided that safety in the past, the conservative choice is to keep it. In case 1, though, the object lookup is a definite noop; we know about the object because we found it in the object database. There is no new information gained by making the call. This patch detects that case and optimizes out the call. Here are best-of-five timings for linux.git: [before] $ time git cat-file --buffer \ --batch-all-objects \ --batch-check='%(objectname)' real 0m2.117s user 0m2.044s sys 0m0.072s [after] $ time git cat-file --buffer \ --batch-all-objects \ --batch-check='%(objectname)' real 0m1.230s user 0m1.176s sys 0m0.052s There are two implementation details to note here. One is that we detect the noop case by seeing that "struct object_info" does not request any information. But besides object existence, there is one other piece of information which sha1_object_info may fill in: whether the object is cached, loose, or packed. We don't currently provide that information in the output, but if we were to do so later, we'd need to take note and disable the optimization in that case. And that leads to the second note. If we were to output that information, a better implementation would be to remember where we saw the object in --batch-all-objects in the first place, and avoid looking it up again by sha1. In fact, we could probably squeeze out some extra performance for less-trivial cases, too, by remembering the pack location where we saw the object, and going directly there to find its information (like type, size, etc). That would in theory make this optimization unnecessary. I didn't pursue that path here for two reasons: 1. It's non-trivial to implement, and has memory implications. Because we sort and de-dup the list of output sha1s, we'd have to record the pack information for each object, too. 2. It doesn't save as much as you might hope. It saves the find_pack_entry() call, but getting the size and type for deltified objects requires walking down the delta chain (for the real type) or reading the delta data header (for the size). These costs tend to dominate the non-trivial cases. By contrast, this optimization is easy and self-contained, and speeds up a real-world case I've used. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
537 lines
14 KiB
C
537 lines
14 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*/
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#include "cache.h"
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#include "builtin.h"
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#include "parse-options.h"
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#include "userdiff.h"
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#include "streaming.h"
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#include "tree-walk.h"
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#include "sha1-array.h"
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struct batch_options {
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int enabled;
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int follow_symlinks;
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int print_contents;
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int buffer_output;
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int all_objects;
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const char *format;
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};
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static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
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int unknown_type)
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{
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unsigned char sha1[20];
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enum object_type type;
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char *buf;
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unsigned long size;
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struct object_context obj_context;
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struct object_info oi = {NULL};
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struct strbuf sb = STRBUF_INIT;
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unsigned flags = LOOKUP_REPLACE_OBJECT;
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if (unknown_type)
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flags |= LOOKUP_UNKNOWN_OBJECT;
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if (get_sha1_with_context(obj_name, 0, sha1, &obj_context))
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die("Not a valid object name %s", obj_name);
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buf = NULL;
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switch (opt) {
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case 't':
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oi.typename = &sb;
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if (sha1_object_info_extended(sha1, &oi, flags) < 0)
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die("git cat-file: could not get object info");
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if (sb.len) {
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printf("%s\n", sb.buf);
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strbuf_release(&sb);
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return 0;
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}
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break;
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case 's':
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oi.sizep = &size;
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if (sha1_object_info_extended(sha1, &oi, flags) < 0)
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die("git cat-file: could not get object info");
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printf("%lu\n", size);
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return 0;
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case 'e':
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return !has_sha1_file(sha1);
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case 'c':
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if (!obj_context.path[0])
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die("git cat-file --textconv %s: <object> must be <sha1:path>",
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obj_name);
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if (textconv_object(obj_context.path, obj_context.mode, sha1, 1, &buf, &size))
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break;
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case 'p':
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type = sha1_object_info(sha1, NULL);
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if (type < 0)
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die("Not a valid object name %s", obj_name);
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/* custom pretty-print here */
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if (type == OBJ_TREE) {
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const char *ls_args[3] = { NULL };
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ls_args[0] = "ls-tree";
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ls_args[1] = obj_name;
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return cmd_ls_tree(2, ls_args, NULL);
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}
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if (type == OBJ_BLOB)
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return stream_blob_to_fd(1, sha1, NULL, 0);
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buf = read_sha1_file(sha1, &type, &size);
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if (!buf)
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die("Cannot read object %s", obj_name);
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/* otherwise just spit out the data */
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break;
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case 0:
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if (type_from_string(exp_type) == OBJ_BLOB) {
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unsigned char blob_sha1[20];
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if (sha1_object_info(sha1, NULL) == OBJ_TAG) {
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char *buffer = read_sha1_file(sha1, &type, &size);
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const char *target;
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if (!skip_prefix(buffer, "object ", &target) ||
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get_sha1_hex(target, blob_sha1))
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die("%s not a valid tag", sha1_to_hex(sha1));
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free(buffer);
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} else
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hashcpy(blob_sha1, sha1);
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if (sha1_object_info(blob_sha1, NULL) == OBJ_BLOB)
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return stream_blob_to_fd(1, blob_sha1, NULL, 0);
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/*
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* we attempted to dereference a tag to a blob
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* and failed; there may be new dereference
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* mechanisms this code is not aware of.
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* fall-back to the usual case.
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*/
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}
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buf = read_object_with_reference(sha1, exp_type, &size, NULL);
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break;
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default:
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die("git cat-file: unknown option: %s", exp_type);
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}
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if (!buf)
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die("git cat-file %s: bad file", obj_name);
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write_or_die(1, buf, size);
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return 0;
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}
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struct expand_data {
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unsigned char sha1[20];
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enum object_type type;
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unsigned long size;
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unsigned long disk_size;
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const char *rest;
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unsigned char delta_base_sha1[20];
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/*
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* If mark_query is true, we do not expand anything, but rather
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* just mark the object_info with items we wish to query.
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*/
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int mark_query;
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/*
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* Whether to split the input on whitespace before feeding it to
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* get_sha1; this is decided during the mark_query phase based on
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* whether we have a %(rest) token in our format.
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*/
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int split_on_whitespace;
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/*
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* After a mark_query run, this object_info is set up to be
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* passed to sha1_object_info_extended. It will point to the data
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* elements above, so you can retrieve the response from there.
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*/
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struct object_info info;
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/*
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* This flag will be true if the requested batch format and options
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* don't require us to call sha1_object_info, which can then be
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* optimized out.
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*/
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unsigned skip_object_info : 1;
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};
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static int is_atom(const char *atom, const char *s, int slen)
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{
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int alen = strlen(atom);
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return alen == slen && !memcmp(atom, s, alen);
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}
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static void expand_atom(struct strbuf *sb, const char *atom, int len,
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void *vdata)
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{
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struct expand_data *data = vdata;
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if (is_atom("objectname", atom, len)) {
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if (!data->mark_query)
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strbuf_addstr(sb, sha1_to_hex(data->sha1));
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} else if (is_atom("objecttype", atom, len)) {
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if (data->mark_query)
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data->info.typep = &data->type;
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else
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strbuf_addstr(sb, typename(data->type));
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} else if (is_atom("objectsize", atom, len)) {
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if (data->mark_query)
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data->info.sizep = &data->size;
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else
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strbuf_addf(sb, "%lu", data->size);
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} else if (is_atom("objectsize:disk", atom, len)) {
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if (data->mark_query)
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data->info.disk_sizep = &data->disk_size;
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else
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strbuf_addf(sb, "%lu", data->disk_size);
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} else if (is_atom("rest", atom, len)) {
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if (data->mark_query)
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data->split_on_whitespace = 1;
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else if (data->rest)
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strbuf_addstr(sb, data->rest);
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} else if (is_atom("deltabase", atom, len)) {
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if (data->mark_query)
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data->info.delta_base_sha1 = data->delta_base_sha1;
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else
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strbuf_addstr(sb, sha1_to_hex(data->delta_base_sha1));
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} else
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die("unknown format element: %.*s", len, atom);
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}
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static size_t expand_format(struct strbuf *sb, const char *start, void *data)
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{
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const char *end;
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if (*start != '(')
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return 0;
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end = strchr(start + 1, ')');
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if (!end)
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die("format element '%s' does not end in ')'", start);
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expand_atom(sb, start + 1, end - start - 1, data);
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return end - start + 1;
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}
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static void batch_write(struct batch_options *opt, const void *data, int len)
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{
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if (opt->buffer_output) {
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if (fwrite(data, 1, len, stdout) != len)
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die_errno("unable to write to stdout");
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} else
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write_or_die(1, data, len);
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}
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static void print_object_or_die(struct batch_options *opt, struct expand_data *data)
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{
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const unsigned char *sha1 = data->sha1;
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assert(data->info.typep);
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if (data->type == OBJ_BLOB) {
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if (opt->buffer_output)
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fflush(stdout);
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if (stream_blob_to_fd(1, sha1, NULL, 0) < 0)
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die("unable to stream %s to stdout", sha1_to_hex(sha1));
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}
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else {
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enum object_type type;
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unsigned long size;
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void *contents;
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contents = read_sha1_file(sha1, &type, &size);
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if (!contents)
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die("object %s disappeared", sha1_to_hex(sha1));
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if (type != data->type)
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die("object %s changed type!?", sha1_to_hex(sha1));
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if (data->info.sizep && size != data->size)
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die("object %s changed size!?", sha1_to_hex(sha1));
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batch_write(opt, contents, size);
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free(contents);
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}
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}
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static void batch_object_write(const char *obj_name, struct batch_options *opt,
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struct expand_data *data)
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{
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struct strbuf buf = STRBUF_INIT;
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if (!data->skip_object_info &&
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sha1_object_info_extended(data->sha1, &data->info, LOOKUP_REPLACE_OBJECT) < 0) {
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printf("%s missing\n", obj_name ? obj_name : sha1_to_hex(data->sha1));
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fflush(stdout);
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return;
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}
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strbuf_expand(&buf, opt->format, expand_format, data);
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strbuf_addch(&buf, '\n');
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batch_write(opt, buf.buf, buf.len);
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strbuf_release(&buf);
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if (opt->print_contents) {
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print_object_or_die(opt, data);
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batch_write(opt, "\n", 1);
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}
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}
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static void batch_one_object(const char *obj_name, struct batch_options *opt,
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struct expand_data *data)
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{
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struct object_context ctx;
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int flags = opt->follow_symlinks ? GET_SHA1_FOLLOW_SYMLINKS : 0;
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enum follow_symlinks_result result;
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result = get_sha1_with_context(obj_name, flags, data->sha1, &ctx);
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if (result != FOUND) {
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switch (result) {
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case MISSING_OBJECT:
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printf("%s missing\n", obj_name);
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break;
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case DANGLING_SYMLINK:
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printf("dangling %"PRIuMAX"\n%s\n",
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(uintmax_t)strlen(obj_name), obj_name);
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break;
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case SYMLINK_LOOP:
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printf("loop %"PRIuMAX"\n%s\n",
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(uintmax_t)strlen(obj_name), obj_name);
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break;
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case NOT_DIR:
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printf("notdir %"PRIuMAX"\n%s\n",
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(uintmax_t)strlen(obj_name), obj_name);
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break;
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default:
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die("BUG: unknown get_sha1_with_context result %d\n",
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result);
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break;
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}
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fflush(stdout);
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return;
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}
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if (ctx.mode == 0) {
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printf("symlink %"PRIuMAX"\n%s\n",
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(uintmax_t)ctx.symlink_path.len,
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ctx.symlink_path.buf);
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fflush(stdout);
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return;
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}
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batch_object_write(obj_name, opt, data);
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}
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struct object_cb_data {
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struct batch_options *opt;
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struct expand_data *expand;
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};
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static void batch_object_cb(const unsigned char sha1[20], void *vdata)
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{
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struct object_cb_data *data = vdata;
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hashcpy(data->expand->sha1, sha1);
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batch_object_write(NULL, data->opt, data->expand);
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}
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static int batch_loose_object(const unsigned char *sha1,
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const char *path,
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void *data)
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{
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sha1_array_append(data, sha1);
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return 0;
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}
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static int batch_packed_object(const unsigned char *sha1,
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struct packed_git *pack,
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uint32_t pos,
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void *data)
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{
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sha1_array_append(data, sha1);
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return 0;
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}
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static int batch_objects(struct batch_options *opt)
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{
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struct strbuf buf = STRBUF_INIT;
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struct expand_data data;
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int save_warning;
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int retval = 0;
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if (!opt->format)
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opt->format = "%(objectname) %(objecttype) %(objectsize)";
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/*
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* Expand once with our special mark_query flag, which will prime the
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* object_info to be handed to sha1_object_info_extended for each
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* object.
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*/
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memset(&data, 0, sizeof(data));
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data.mark_query = 1;
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strbuf_expand(&buf, opt->format, expand_format, &data);
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data.mark_query = 0;
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if (opt->all_objects) {
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struct object_info empty;
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memset(&empty, 0, sizeof(empty));
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if (!memcmp(&data.info, &empty, sizeof(empty)))
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data.skip_object_info = 1;
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}
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/*
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* If we are printing out the object, then always fill in the type,
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* since we will want to decide whether or not to stream.
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*/
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if (opt->print_contents)
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data.info.typep = &data.type;
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if (opt->all_objects) {
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struct sha1_array sa = SHA1_ARRAY_INIT;
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struct object_cb_data cb;
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for_each_loose_object(batch_loose_object, &sa, 0);
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for_each_packed_object(batch_packed_object, &sa, 0);
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cb.opt = opt;
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cb.expand = &data;
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sha1_array_for_each_unique(&sa, batch_object_cb, &cb);
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sha1_array_clear(&sa);
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return 0;
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}
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/*
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* We are going to call get_sha1 on a potentially very large number of
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* objects. In most large cases, these will be actual object sha1s. The
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* cost to double-check that each one is not also a ref (just so we can
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* warn) ends up dwarfing the actual cost of the object lookups
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* themselves. We can work around it by just turning off the warning.
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*/
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save_warning = warn_on_object_refname_ambiguity;
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warn_on_object_refname_ambiguity = 0;
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while (strbuf_getline(&buf, stdin, '\n') != EOF) {
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if (data.split_on_whitespace) {
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/*
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* Split at first whitespace, tying off the beginning
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* of the string and saving the remainder (or NULL) in
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* data.rest.
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*/
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char *p = strpbrk(buf.buf, " \t");
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if (p) {
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while (*p && strchr(" \t", *p))
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*p++ = '\0';
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}
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data.rest = p;
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}
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batch_one_object(buf.buf, opt, &data);
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}
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strbuf_release(&buf);
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warn_on_object_refname_ambiguity = save_warning;
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return retval;
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}
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static const char * const cat_file_usage[] = {
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N_("git cat-file (-t [--allow-unknown-type]|-s [--allow-unknown-type]|-e|-p|<type>|--textconv) <object>"),
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N_("git cat-file (--batch | --batch-check) [--follow-symlinks]"),
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NULL
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};
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static int git_cat_file_config(const char *var, const char *value, void *cb)
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{
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if (userdiff_config(var, value) < 0)
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return -1;
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return git_default_config(var, value, cb);
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}
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static int batch_option_callback(const struct option *opt,
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const char *arg,
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int unset)
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{
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struct batch_options *bo = opt->value;
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if (bo->enabled) {
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return 1;
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}
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bo->enabled = 1;
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bo->print_contents = !strcmp(opt->long_name, "batch");
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bo->format = arg;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int cmd_cat_file(int argc, const char **argv, const char *prefix)
|
|
{
|
|
int opt = 0;
|
|
const char *exp_type = NULL, *obj_name = NULL;
|
|
struct batch_options batch = {0};
|
|
int unknown_type = 0;
|
|
|
|
const struct option options[] = {
|
|
OPT_GROUP(N_("<type> can be one of: blob, tree, commit, tag")),
|
|
OPT_CMDMODE('t', NULL, &opt, N_("show object type"), 't'),
|
|
OPT_CMDMODE('s', NULL, &opt, N_("show object size"), 's'),
|
|
OPT_CMDMODE('e', NULL, &opt,
|
|
N_("exit with zero when there's no error"), 'e'),
|
|
OPT_CMDMODE('p', NULL, &opt, N_("pretty-print object's content"), 'p'),
|
|
OPT_CMDMODE(0, "textconv", &opt,
|
|
N_("for blob objects, run textconv on object's content"), 'c'),
|
|
OPT_BOOL(0, "allow-unknown-type", &unknown_type,
|
|
N_("allow -s and -t to work with broken/corrupt objects")),
|
|
OPT_BOOL(0, "buffer", &batch.buffer_output, N_("buffer --batch output")),
|
|
{ OPTION_CALLBACK, 0, "batch", &batch, "format",
|
|
N_("show info and content of objects fed from the standard input"),
|
|
PARSE_OPT_OPTARG, batch_option_callback },
|
|
{ OPTION_CALLBACK, 0, "batch-check", &batch, "format",
|
|
N_("show info about objects fed from the standard input"),
|
|
PARSE_OPT_OPTARG, batch_option_callback },
|
|
OPT_BOOL(0, "follow-symlinks", &batch.follow_symlinks,
|
|
N_("follow in-tree symlinks (used with --batch or --batch-check)")),
|
|
OPT_BOOL(0, "batch-all-objects", &batch.all_objects,
|
|
N_("show all objects with --batch or --batch-check")),
|
|
OPT_END()
|
|
};
|
|
|
|
git_config(git_cat_file_config, NULL);
|
|
|
|
argc = parse_options(argc, argv, prefix, options, cat_file_usage, 0);
|
|
|
|
if (opt) {
|
|
if (argc == 1)
|
|
obj_name = argv[0];
|
|
else
|
|
usage_with_options(cat_file_usage, options);
|
|
}
|
|
if (!opt && !batch.enabled) {
|
|
if (argc == 2) {
|
|
exp_type = argv[0];
|
|
obj_name = argv[1];
|
|
} else
|
|
usage_with_options(cat_file_usage, options);
|
|
}
|
|
if (batch.enabled && (opt || argc)) {
|
|
usage_with_options(cat_file_usage, options);
|
|
}
|
|
|
|
if ((batch.follow_symlinks || batch.all_objects) && !batch.enabled) {
|
|
usage_with_options(cat_file_usage, options);
|
|
}
|
|
|
|
if (batch.enabled)
|
|
return batch_objects(&batch);
|
|
|
|
if (unknown_type && opt != 't' && opt != 's')
|
|
die("git cat-file --allow-unknown-type: use with -s or -t");
|
|
return cat_one_file(opt, exp_type, obj_name, unknown_type);
|
|
}
|