From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id 284FD1F9FF for ; Tue, 30 Mar 2021 15:05:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232298AbhC3PE4 (ORCPT ); Tue, 30 Mar 2021 11:04:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232249AbhC3PE3 (ORCPT ); Tue, 30 Mar 2021 11:04:29 -0400 Received: from mail-qk1-x731.google.com (mail-qk1-x731.google.com [IPv6:2607:f8b0:4864:20::731]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 676A0C061574 for ; Tue, 30 Mar 2021 08:04:29 -0700 (PDT) Received: by mail-qk1-x731.google.com with SMTP id y5so16130608qkl.9 for ; Tue, 30 Mar 2021 08:04:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ttaylorr-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=xklA/J4YMarRCg2zjTV1xfE1mmzJQEg1xUYjYS6whic=; b=lawUqpn78u3Bk5iuOG6T7eehL0ig7mhrHbPpJ1Rs1gw1FkOuzHPpKOTchJ94f6J3Gh lSOXtFfJf6MWqSmoJOTWPnbMkeztd9RR+5bDF40MDP+DgnuaMWf9cxVFzJU+pcufeECc kGuTv6nv3jE5OtpSgaX/4T1RKXhbflNItoTjHn3+dwJNFGD4dw5mbJ+MgVc5Ysxg4dlE Hha7QhxGrrMvsw2ZjjtX8BZNFo9pcgjadS6T40IWnBxlaeHOV22nXnRj+TdTKOxjn8XE L+ovPHh5keUWSeXLe2VCGu94MMP+uadO9xmu/WP5r5SEiR8IwFBPbPLrYL55Qz8pQPTH noRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=xklA/J4YMarRCg2zjTV1xfE1mmzJQEg1xUYjYS6whic=; b=QlV6USzrSGQ5JFdX3Z2ZNvtO5y8dqR7VNan3pEj/ScXG1yZ4k1yx+/he1IuTwojA2l CfFDgRhgPx8R0Y3nia3Agknd0qiAdipk+wnfV8OFZ5AP8ZsbJCf9JMlCT3j0C2bUyS3Y EgeenRtVgNZIN/VXF9DTME55aUEYLlhO6eib2DMyR87lYx9Gt81s4hmqko/drmVkUU02 39O2TmulyVdjWK84MRqy6/SRVBtxGAMx4r1x10g/AjU0WJwrkxNgsHnu5bKoebMwhNKj MMTdK6JXDFthMFi7mxXhctBuXNKOsJBSgyYcRlVJ5HkPYHlvVlJBi87D0Pp4XAlshDyE gshg== X-Gm-Message-State: AOAM530s4zChxbpKYtcplc6XO7nFxDSVC/aK42YLK7LFQ7i3ulQ94kIK 4Iu3q8YdQQ5HyTlk6dr2KzR0lOMoWgXTkg== X-Google-Smtp-Source: ABdhPJyKvvbEa0Nz6p+WoPN3vypZLulH+XmuPvnBI2NkboJvokW1KZY4PsjvJ46dbD7YjDwir5pCfw== X-Received: by 2002:a37:9dc1:: with SMTP id g184mr32255433qke.285.1617116668167; Tue, 30 Mar 2021 08:04:28 -0700 (PDT) Received: from localhost ([2605:9480:22e:ff10:7b00:4f79:8763:6261]) by smtp.gmail.com with ESMTPSA id g2sm13474453qtu.0.2021.03.30.08.04.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Mar 2021 08:04:27 -0700 (PDT) Date: Tue, 30 Mar 2021 11:04:26 -0400 From: Taylor Blau To: git@vger.kernel.org Cc: gitster@pobox.com, peff@peff.net, dstolee@microsoft.com, jonathantanmy@google.com Subject: [PATCH v4 13/16] pack-revindex: read multi-pack reverse indexes Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Implement reading for multi-pack reverse indexes, as described in the previous patch. Note that these functions don't yet have any callers, and won't until multi-pack reachability bitmaps are introduced in a later patch series. In the meantime, this patch implements some of the infrastructure necessary to support multi-pack bitmaps. There are three new functions exposed by the revindex API: - load_midx_revindex(): loads the reverse index corresponding to the given multi-pack index. - midx_to_pack_pos() and pack_pos_to_midx(): these convert between the multi-pack index and pseudo-pack order. load_midx_revindex() and pack_pos_to_midx() are both relatively straightforward. load_midx_revindex() needs a few functions to be exposed from the midx API. One to get the checksum of a midx, and another to get the .rev's filename. Similar to recent changes in the packed_git struct, three new fields are added to the multi_pack_index struct: one to keep track of the size, one to keep track of the mmap'd pointer, and another to point past the header and at the reverse index's data. pack_pos_to_midx() simply reads the corresponding entry out of the table. midx_to_pack_pos() is the trickiest, since it needs to find an object's position in the psuedo-pack order, but that order can only be recovered in the .rev file itself. This mapping can be implemented with a binary search, but note that the thing we're binary searching over isn't an array of values, but rather a permuted order of those values. So, when comparing two items, it's helpful to keep in mind the difference. Instead of a traditional binary search, where you are comparing two things directly, here we're comparing a (pack, offset) tuple with an index into the multi-pack index. That index describes another (pack, offset) tuple, and it is _those_ two tuples that are compared. Signed-off-by: Taylor Blau --- midx.c | 11 +++++ midx.h | 6 +++ pack-revindex.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++++ pack-revindex.h | 53 ++++++++++++++++++++ packfile.c | 3 ++ 5 files changed, 199 insertions(+) diff --git a/midx.c b/midx.c index 2173a9b45c..c04e794888 100644 --- a/midx.c +++ b/midx.c @@ -47,11 +47,22 @@ static uint8_t oid_version(void) } } +static const unsigned char *get_midx_checksum(struct multi_pack_index *m) +{ + return m->data + m->data_len - the_hash_algo->rawsz; +} + static char *get_midx_filename(const char *object_dir) { return xstrfmt("%s/pack/multi-pack-index", object_dir); } +char *get_midx_rev_filename(struct multi_pack_index *m) +{ + return xstrfmt("%s/pack/multi-pack-index-%s.rev", + m->object_dir, hash_to_hex(get_midx_checksum(m))); +} + static int midx_read_oid_fanout(const unsigned char *chunk_start, size_t chunk_size, void *data) { diff --git a/midx.h b/midx.h index 93bd68189e..0a8294d2ee 100644 --- a/midx.h +++ b/midx.h @@ -15,6 +15,10 @@ struct multi_pack_index { const unsigned char *data; size_t data_len; + const uint32_t *revindex_data; + const uint32_t *revindex_map; + size_t revindex_len; + uint32_t signature; unsigned char version; unsigned char hash_len; @@ -37,6 +41,8 @@ struct multi_pack_index { #define MIDX_PROGRESS (1 << 0) +char *get_midx_rev_filename(struct multi_pack_index *m); + struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local); int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id); int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result); diff --git a/pack-revindex.c b/pack-revindex.c index 4262530449..0e4a31d9db 100644 --- a/pack-revindex.c +++ b/pack-revindex.c @@ -3,6 +3,7 @@ #include "object-store.h" #include "packfile.h" #include "config.h" +#include "midx.h" struct revindex_entry { off_t offset; @@ -293,6 +294,43 @@ int load_pack_revindex(struct packed_git *p) return -1; } +int load_midx_revindex(struct multi_pack_index *m) +{ + char *revindex_name; + int ret; + if (m->revindex_data) + return 0; + + revindex_name = get_midx_rev_filename(m); + + ret = load_revindex_from_disk(revindex_name, + m->num_objects, + &m->revindex_map, + &m->revindex_len); + if (ret) + goto cleanup; + + m->revindex_data = (const uint32_t *)((const char *)m->revindex_map + RIDX_HEADER_SIZE); + +cleanup: + free(revindex_name); + return ret; +} + +int close_midx_revindex(struct multi_pack_index *m) +{ + if (!m || !m->revindex_map) + return 0; + + munmap((void*)m->revindex_map, m->revindex_len); + + m->revindex_map = NULL; + m->revindex_data = NULL; + m->revindex_len = 0; + + return 0; +} + int offset_to_pack_pos(struct packed_git *p, off_t ofs, uint32_t *pos) { unsigned lo, hi; @@ -347,3 +385,91 @@ off_t pack_pos_to_offset(struct packed_git *p, uint32_t pos) else return nth_packed_object_offset(p, pack_pos_to_index(p, pos)); } + +uint32_t pack_pos_to_midx(struct multi_pack_index *m, uint32_t pos) +{ + if (!m->revindex_data) + BUG("pack_pos_to_midx: reverse index not yet loaded"); + if (m->num_objects <= pos) + BUG("pack_pos_to_midx: out-of-bounds object at %"PRIu32, pos); + return get_be32(m->revindex_data + pos); +} + +struct midx_pack_key { + uint32_t pack; + off_t offset; + + uint32_t preferred_pack; + struct multi_pack_index *midx; +}; + +static int midx_pack_order_cmp(const void *va, const void *vb) +{ + const struct midx_pack_key *key = va; + struct multi_pack_index *midx = key->midx; + + uint32_t versus = pack_pos_to_midx(midx, (uint32_t*)vb - (const uint32_t *)midx->revindex_data); + uint32_t versus_pack = nth_midxed_pack_int_id(midx, versus); + off_t versus_offset; + + uint32_t key_preferred = key->pack == key->preferred_pack; + uint32_t versus_preferred = versus_pack == key->preferred_pack; + + /* + * First, compare the preferred-ness, noting that the preferred pack + * comes first. + */ + if (key_preferred && !versus_preferred) + return -1; + else if (!key_preferred && versus_preferred) + return 1; + + /* Then, break ties first by comparing the pack IDs. */ + if (key->pack < versus_pack) + return -1; + else if (key->pack > versus_pack) + return 1; + + /* Finally, break ties by comparing offsets within a pack. */ + versus_offset = nth_midxed_offset(midx, versus); + if (key->offset < versus_offset) + return -1; + else if (key->offset > versus_offset) + return 1; + + return 0; +} + +int midx_to_pack_pos(struct multi_pack_index *m, uint32_t at, uint32_t *pos) +{ + struct midx_pack_key key; + uint32_t *found; + + if (!m->revindex_data) + BUG("midx_to_pack_pos: reverse index not yet loaded"); + if (m->num_objects <= at) + BUG("midx_to_pack_pos: out-of-bounds object at %"PRIu32, at); + + key.pack = nth_midxed_pack_int_id(m, at); + key.offset = nth_midxed_offset(m, at); + key.midx = m; + /* + * The preferred pack sorts first, so determine its identifier by + * looking at the first object in pseudo-pack order. + * + * Note that if no --preferred-pack is explicitly given when writing a + * multi-pack index, then whichever pack has the lowest identifier + * implicitly is preferred (and includes all its objects, since ties are + * broken first by pack identifier). + */ + key.preferred_pack = nth_midxed_pack_int_id(m, pack_pos_to_midx(m, 0)); + + found = bsearch(&key, m->revindex_data, m->num_objects, + sizeof(*m->revindex_data), midx_pack_order_cmp); + + if (!found) + return error("bad offset for revindex"); + + *pos = found - m->revindex_data; + return 0; +} diff --git a/pack-revindex.h b/pack-revindex.h index ba7c82c125..479b8f2f9c 100644 --- a/pack-revindex.h +++ b/pack-revindex.h @@ -14,6 +14,20 @@ * * - offset: the byte offset within the .pack file at which the object contents * can be found + * + * The revindex can also be used with a multi-pack index (MIDX). In this + * setting: + * + * - index position refers to an object's numeric position within the MIDX + * + * - pack position refers to an object's position within a non-existent pack + * described by the MIDX. The pack structure is described in + * Documentation/technical/pack-format.txt. + * + * It is effectively a concatanation of all packs in the MIDX (ordered by + * their numeric ID within the MIDX) in their original order within each + * pack), removing duplicates, and placing the preferred pack (if any) + * first. */ @@ -24,6 +38,7 @@ #define GIT_TEST_REV_INDEX_DIE_IN_MEMORY "GIT_TEST_REV_INDEX_DIE_IN_MEMORY" struct packed_git; +struct multi_pack_index; /* * load_pack_revindex populates the revindex's internal data-structures for the @@ -34,6 +49,22 @@ struct packed_git; */ int load_pack_revindex(struct packed_git *p); +/* + * load_midx_revindex loads the '.rev' file corresponding to the given + * multi-pack index by mmap-ing it and assigning pointers in the + * multi_pack_index to point at it. + * + * A negative number is returned on error. + */ +int load_midx_revindex(struct multi_pack_index *m); + +/* + * Frees resources associated with a multi-pack reverse index. + * + * A negative number is returned on error. + */ +int close_midx_revindex(struct multi_pack_index *m); + /* * offset_to_pack_pos converts an object offset to a pack position. This * function returns zero on success, and a negative number otherwise. The @@ -71,4 +102,26 @@ uint32_t pack_pos_to_index(struct packed_git *p, uint32_t pos); */ off_t pack_pos_to_offset(struct packed_git *p, uint32_t pos); +/* + * pack_pos_to_midx converts the object at position "pos" within the MIDX + * pseudo-pack into a MIDX position. + * + * If the reverse index has not yet been loaded, or the position is out of + * bounds, this function aborts. + * + * This function runs in time O(log N) with the number of objects in the MIDX. + */ +uint32_t pack_pos_to_midx(struct multi_pack_index *m, uint32_t pos); + +/* + * midx_to_pack_pos converts from the MIDX-relative position at "at" to the + * corresponding pack position. + * + * If the reverse index has not yet been loaded, or the position is out of + * bounds, this function aborts. + * + * This function runs in constant time. + */ +int midx_to_pack_pos(struct multi_pack_index *midx, uint32_t at, uint32_t *pos); + #endif diff --git a/packfile.c b/packfile.c index 6661f3325a..8668345d93 100644 --- a/packfile.c +++ b/packfile.c @@ -862,6 +862,9 @@ static void prepare_pack(const char *full_name, size_t full_name_len, if (!strcmp(file_name, "multi-pack-index")) return; + if (starts_with(file_name, "multi-pack-index") && + ends_with(file_name, ".rev")) + return; if (ends_with(file_name, ".idx") || ends_with(file_name, ".rev") || ends_with(file_name, ".pack") || -- 2.30.0.667.g81c0cbc6fd