From a3437b8c26a63d971437c8b6ac6f6d4f632be548 Mon Sep 17 00:00:00 2001 From: "jon@blackcubes.dyndns.org" Date: Mon, 6 Jun 2005 15:39:40 +0000 Subject: [PATCH] [PATCH] Modify git-rev-list to linearise the commit history in merge order. This patch linearises the GIT commit history graph into merge order which is defined by invariants specified in Documentation/git-rev-list.txt. The linearisation produced by this patch is superior in an objective sense to that produced by the existing git-rev-list implementation in that the linearisation produced is guaranteed to have the minimum number of discontinuities, where a discontinuity is defined as an adjacent pair of commits in the output list which are not related in a direct child-parent relationship. With this patch a graph like this: a4 --- | \ \ | b4 | |/ | | a3 | | | | | a2 | | | | c3 | | | | | c2 | b3 | | | /| | b2 | | | c1 | | / | b1 a1 | | | a0 | | / root Sorts like this: = a4 | c3 | c2 | c1 ^ b4 | b3 | b2 | b1 ^ a3 | a2 | a1 | a0 = root Instead of this: = a4 | c3 ^ b4 | a3 ^ c2 ^ b3 ^ a2 ^ b2 ^ c1 ^ a1 ^ b1 ^ a0 = root A test script, t/t6000-rev-list.sh, includes a test which demonstrates that the linearisation produced by --merge-order has less discontinuities than the linearisation produced by git-rev-list without the --merge-order flag specified. To see this, do the following: cd t ./t6000-rev-list.sh cd trash cat actual-default-order cat actual-merge-order The existing behaviour of git-rev-list is preserved, by default. To obtain the modified behaviour, specify --merge-order or --merge-order --show-breaks on the command line. This version of the patch has been tested on the git repository and also on the linux-2.6 repository and has reasonable performance on both - ~50-100% slower than the original algorithm. This version of the patch has incorporated a functional equivalent of the Linus' output limiting algorithm into the merge-order algorithm itself. This operates per the notes associated with Linus' commit 337cb3fb8da45f10fe9a0c3cf571600f55ead2ce. This version has incorporated Linus' feedback regarding proposed changes to rev-list.c. (see: [PATCH] Factor out filtering in rev-list.c) This version has improved the way sort_first_epoch marks commits as uninteresting. For more details about this change, refer to Documentation/git-rev-list.txt and http://blackcubes.dyndns.org/epoch/. Signed-off-by: Jon Seymour Signed-off-by: Linus Torvalds --- Documentation/git-rev-list.txt | 30 +- Makefile | 5 +- commit.c | 24 +- commit.h | 4 + epoch.c | 693 +++++++++++++++++++++++++++++++++ epoch.h | 20 + object.h | 1 + rev-list.c | 81 +++- 8 files changed, 840 insertions(+), 18 deletions(-) create mode 100644 epoch.c create mode 100644 epoch.h diff --git a/Documentation/git-rev-list.txt b/Documentation/git-rev-list.txt index f2c5fa9f4c..3cfa58b5bd 100644 --- a/Documentation/git-rev-list.txt +++ b/Documentation/git-rev-list.txt @@ -9,7 +9,7 @@ git-rev-list - Lists commit objects in reverse chronological order SYNOPSIS -------- -'git-rev-list' +'git-rev-list' [ *--max-count*=number ] [ *--max-age*=timestamp ] [ *--min-age*=timestamp ] [ *--merge-order* [ *--show-breaks* ] ] DESCRIPTION ----------- @@ -17,11 +17,39 @@ Lists commit objects in reverse chronological order starting at the given commit, taking ancestry relationship into account. This is useful to produce human-readable log output. +If *--merge-order* is specified, the commit history is decomposed into a unique sequence of minimal, non-linear +epochs and maximal, linear epochs. Non-linear epochs are then linearised by sorting them into merge order, which +is described below. + +Maximal, linear epochs correspond to periods of sequential development. Minimal, non-linear epochs +correspond to periods of divergent development followed by a converging merge. The theory of epochs is described +in more detail at link:http://blackcubes.dyndns.org/epoch/[http://blackcubes.dyndns.org/epoch/]. + +The merge order for a non-linear epoch is defined as a linearisation for which the following invariants are true: + + 1. if a commit P is reachable from commit N, commit P sorts after commit N in the linearised list. + 2. if Pi and Pj are any two parents of a merge M (with i < j), then any commit N, such that N is reachable from Pj + but not reachable from Pi, sorts before all commits reachable from Pi. + +Invariant 1 states that later commits appear before earlier commits they are derived from. + +Invariant 2 states that commits unique to "later" parents in a merge, appear before all commits from "earlier" parents of +a merge. + +If *--show-breaks* is specified, each item of the list is output with a 2-character prefix consisting of one of: + (|), (^), (=) followed by a space. +Commits marked with (=) represent the boundaries of minimal, non-linear epochs and correspond either to the start of a period of divergent development or to the end of such a period. +Commits marked with (|) are direct parents of commits immediately preceding the marked commit in the list. +Commits marked with (^) are not parents of the immediately preceding commit. These "breaks" represent necessary discontinuities implied by trying to represent an arbtirary DAG in a linear form. + +*--show-breaks* is only valid if *--merge-order* is also specified. Author ------ Written by Linus Torvalds +Original *--merge-order* logic by Jon Seymour + Documentation -------------- Documentation by David Greaves, Junio C Hamano and the git-list . diff --git a/Makefile b/Makefile index a85abd6612..c87cc35af6 100644 --- a/Makefile +++ b/Makefile @@ -40,9 +40,9 @@ install: $(PROG) $(SCRIPTS) $(INSTALL) $(PROG) $(SCRIPTS) $(dest)$(bin) LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \ - tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o + tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o epoch.o LIB_FILE=libgit.a -LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h +LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h epoch.h LIB_H += strbuf.h LIB_OBJS += strbuf.o @@ -135,6 +135,7 @@ diffcore-pathspec.o : $(LIB_H) diffcore.h diffcore-pickaxe.o : $(LIB_H) diffcore.h diffcore-break.o : $(LIB_H) diffcore.h diffcore-order.o : $(LIB_H) diffcore.h +epoch.o: $(LIB_H) test: all $(MAKE) -C t/ all diff --git a/commit.c b/commit.c index 3d3bb1cde8..21ac2fe9d7 100644 --- a/commit.c +++ b/commit.c @@ -130,7 +130,7 @@ void free_commit_list(struct commit_list *list) } } -static void insert_by_date(struct commit_list **list, struct commit *item) +void insert_by_date(struct commit_list **list, struct commit *item) { struct commit_list **pp = list; struct commit_list *p; @@ -280,3 +280,25 @@ unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned l buf[offset] = '\0'; return offset; } + +struct commit *pop_commit(struct commit_list **stack) +{ + struct commit_list *top = *stack; + struct commit *item = top ? top->item : NULL; + + if (top) { + *stack = top->next; + free(top); + } + return item; +} + +int count_parents(struct commit * commit) +{ + int count = 0; + struct commit_list * parents = commit->parents; + for (count=0;parents; parents=parents->next,count++) + ; + return count; +} + diff --git a/commit.h b/commit.h index 85736a89f9..51d95764ab 100644 --- a/commit.h +++ b/commit.h @@ -42,6 +42,7 @@ enum cmit_fmt { extern unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space); +void insert_by_date(struct commit_list **list, struct commit *item); /** Removes the first commit from a list sorted by date, and adds all * of its parents. @@ -49,4 +50,7 @@ extern unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, uns struct commit *pop_most_recent_commit(struct commit_list **list, unsigned int mark); +struct commit *pop_commit(struct commit_list **stack); + +int count_parents(struct commit * commit); #endif /* COMMIT_H */ diff --git a/epoch.c b/epoch.c new file mode 100644 index 0000000000..ba63eac68e --- /dev/null +++ b/epoch.c @@ -0,0 +1,693 @@ +/* + * Copyright (c) 2005, Jon Seymour + * + * For more information about epoch theory on which this module is based, + * refer to http://blackcubes.dyndns.org/epoch/. That web page defines + * terms such as "epoch" and "minimal, non-linear epoch" and provides rationales + * for some of the algorithms used here. + * + */ +#include +#include // provides arbitrary precision integers + // required to accurately represent fractional + //mass + +#include "cache.h" +#include "commit.h" +#include "epoch.h" + +struct fraction { + BIGNUM numerator; + BIGNUM denominator; +}; + +#define HAS_EXACTLY_ONE_PARENT(n) ((n)->parents && !(n)->parents->next) + +static BN_CTX *context = NULL; +static struct fraction *one = NULL; +static struct fraction *zero = NULL; + +static BN_CTX *get_BN_CTX() +{ + if (!context) { + context = BN_CTX_new(); + } + return context; +} + +static struct fraction *new_zero() +{ + struct fraction *result = xmalloc(sizeof(*result)); + BN_init(&result->numerator); + BN_init(&result->denominator); + BN_zero(&result->numerator); + BN_one(&result->denominator); + return result; +} + +static void clear_fraction(struct fraction *fraction) +{ + BN_clear(&fraction->numerator); + BN_clear(&fraction->denominator); +} + +static struct fraction *divide(struct fraction *result, struct fraction *fraction, int divisor) +{ + BIGNUM bn_divisor; + + BN_init(&bn_divisor); + BN_set_word(&bn_divisor, divisor); + + BN_copy(&result->numerator, &fraction->numerator); + BN_mul(&result->denominator, &fraction->denominator, &bn_divisor, get_BN_CTX()); + + BN_clear(&bn_divisor); + return result; +} + +static struct fraction *init_fraction(struct fraction *fraction) +{ + BN_init(&fraction->numerator); + BN_init(&fraction->denominator); + BN_zero(&fraction->numerator); + BN_one(&fraction->denominator); + return fraction; +} + +static struct fraction *get_one() +{ + if (!one) { + one = new_zero(); + BN_one(&one->numerator); + } + return one; +} + +static struct fraction *get_zero() +{ + if (!zero) { + zero = new_zero(); + } + return zero; +} + +static struct fraction *copy(struct fraction *to, struct fraction *from) +{ + BN_copy(&to->numerator, &from->numerator); + BN_copy(&to->denominator, &from->denominator); + return to; +} + +static struct fraction *add(struct fraction *result, struct fraction *left, struct fraction *right) +{ + BIGNUM a, b, gcd; + + BN_init(&a); + BN_init(&b); + BN_init(&gcd); + + BN_mul(&a, &left->numerator, &right->denominator, get_BN_CTX()); + BN_mul(&b, &left->denominator, &right->numerator, get_BN_CTX()); + BN_mul(&result->denominator, &left->denominator, &right->denominator, get_BN_CTX()); + BN_add(&result->numerator, &a, &b); + + BN_gcd(&gcd, &result->denominator, &result->numerator, get_BN_CTX()); + BN_div(&result->denominator, NULL, &result->denominator, &gcd, get_BN_CTX()); + BN_div(&result->numerator, NULL, &result->numerator, &gcd, get_BN_CTX()); + + BN_clear(&a); + BN_clear(&b); + BN_clear(&gcd); + + return result; +} + +static int compare(struct fraction *left, struct fraction *right) +{ + BIGNUM a, b; + + int result; + + BN_init(&a); + BN_init(&b); + + BN_mul(&a, &left->numerator, &right->denominator, get_BN_CTX()); + BN_mul(&b, &left->denominator, &right->numerator, get_BN_CTX()); + + result = BN_cmp(&a, &b); + + BN_clear(&a); + BN_clear(&b); + + return result; +} + +struct mass_counter { + struct fraction seen; + struct fraction pending; +}; + +static struct mass_counter *new_mass_counter(struct commit *commit, struct fraction *pending) +{ + struct mass_counter *mass_counter = xmalloc(sizeof(*mass_counter)); + memset(mass_counter, 0, sizeof(*mass_counter)); + + init_fraction(&mass_counter->seen); + init_fraction(&mass_counter->pending); + + copy(&mass_counter->pending, pending); + copy(&mass_counter->seen, get_zero()); + + if (commit->object.util) { + die("multiple attempts to initialize mass counter for %s\n", sha1_to_hex(commit->object.sha1)); + } + + commit->object.util = mass_counter; + + return mass_counter; +} + +static void free_mass_counter(struct mass_counter *counter) +{ + clear_fraction(&counter->seen); + clear_fraction(&counter->pending); + free(counter); +} + +// +// Finds the base commit of a list of commits. +// +// One property of the commit being searched for is that every commit reachable +// from the base commit is reachable from the commits in the starting list only +// via paths that include the base commit. +// +// This algorithm uses a conservation of mass approach to find the base commit. +// +// We start by injecting one unit of mass into the graph at each +// of the commits in the starting list. Injecting mass into a commit +// is achieved by adding to its pending mass counter and, if it is not already +// enqueued, enqueuing the commit in a list of pending commits, in latest +// commit date first order. +// +// The algorithm then preceeds to visit each commit in the pending queue. +// Upon each visit, the pending mass is added to the mass already seen for that +// commit and then divided into N equal portions, where N is the number of +// parents of the commit being visited. The divided portions are then injected +// into each of the parents. +// +// The algorithm continues until we discover a commit which has seen all the +// mass originally injected or until we run out of things to do. +// +// If we find a commit that has seen all the original mass, we have found +// the common base of all the commits in the starting list. +// +// The algorithm does _not_ depend on accurate timestamps for correct operation. +// However, reasonably sane (e.g. non-random) timestamps are required in order +// to prevent an exponential performance characteristic. The occasional +// timestamp inaccuracy will not dramatically affect performance but may +// result in more nodes being processed than strictly necessary. +// +// This procedure sets *boundary to the address of the base commit. It returns +// non-zero if, and only if, there was a problem parsing one of the +// commits discovered during the traversal. +// +static int find_base_for_list(struct commit_list *list, struct commit **boundary) +{ + + int ret = 0; + + struct commit_list *cleaner = NULL; + struct commit_list *pending = NULL; + + *boundary = NULL; + + struct fraction injected; + + init_fraction(&injected); + + for (; list; list = list->next) { + + struct commit *item = list->item; + + if (item->object.util || (item->object.flags & UNINTERESTING)) { + die("%s:%d:%s: logic error: this should not have happened - commit %s\n", + __FILE__, __LINE__, __FUNCTION__, sha1_to_hex(item->object.sha1)); + } + + new_mass_counter(list->item, get_one()); + add(&injected, &injected, get_one()); + + commit_list_insert(list->item, &cleaner); + commit_list_insert(list->item, &pending); + } + + while (!*boundary && pending && !ret) { + + struct commit *latest = pop_commit(&pending); + + struct mass_counter *latest_node = (struct mass_counter *) latest->object.util; + + if ((ret = parse_commit(latest))) + continue; + + add(&latest_node->seen, &latest_node->seen, &latest_node->pending); + + int num_parents = count_parents(latest); + + if (num_parents) { + + struct fraction distribution; + struct commit_list *parents; + + divide(init_fraction(&distribution), &latest_node->pending, num_parents); + + for (parents = latest->parents; parents; parents = parents->next) { + + struct commit *parent = parents->item; + struct mass_counter *parent_node = (struct mass_counter *) parent->object.util; + + if (!parent_node) { + + parent_node = new_mass_counter(parent, &distribution); + + insert_by_date(&pending, parent); + commit_list_insert(parent, &cleaner); + + } else { + + if (!compare(&parent_node->pending, get_zero())) { + insert_by_date(&pending, parent); + } + add(&parent_node->pending, &parent_node->pending, &distribution); + + } + } + + clear_fraction(&distribution); + + } + + if (!compare(&latest_node->seen, &injected)) { + *boundary = latest; + } + + copy(&latest_node->pending, get_zero()); + + } + + while (cleaner) { + + struct commit *next = pop_commit(&cleaner); + free_mass_counter((struct mass_counter *) next->object.util); + next->object.util = NULL; + + } + + if (pending) + free_commit_list(pending); + + clear_fraction(&injected); + + return ret; + +} + + +// +// Finds the base of an minimal, non-linear epoch, headed at head, by +// applying the find_base_for_list to a list consisting of the parents +// +static int find_base(struct commit *head, struct commit **boundary) +{ + int ret = 0; + struct commit_list *pending = NULL; + struct commit_list *next; + + commit_list_insert(head, &pending); + for (next = head->parents; next; next = next->next) { + commit_list_insert(next->item, &pending); + } + ret = find_base_for_list(pending, boundary); + free_commit_list(pending); + + return ret; +} + +// +// This procedure traverses to the boundary of the first epoch in the epoch +// sequence of the epoch headed at head_of_epoch. This is either the end of +// the maximal linear epoch or the base of a minimal non-linear epoch. +// +// The queue of pending nodes is sorted in reverse date order and each node +// is currently in the queue at most once. +// +static int find_next_epoch_boundary(struct commit *head_of_epoch, struct commit **boundary) +{ + int ret; + struct commit *item = head_of_epoch; + + ret = parse_commit(item); + if (ret) + return ret; + + if (HAS_EXACTLY_ONE_PARENT(item)) { + + // we are at the start of a maximimal linear epoch .. traverse to the end + + // traverse to the end of a maximal linear epoch + while (HAS_EXACTLY_ONE_PARENT(item) && !ret) { + item = item->parents->item; + ret = parse_commit(item); + } + *boundary = item; + + } else { + + // otherwise, we are at the start of a minimal, non-linear + // epoch - find the common base of all parents. + + ret = find_base(item, boundary); + + } + + return ret; +} + +// +// Returns non-zero if parent is known to be a parent of child. +// +static int is_parent_of(struct commit *parent, struct commit *child) +{ + struct commit_list *parents; + for (parents = child->parents; parents; parents = parents->next) { + if (!memcmp(parent->object.sha1, parents->item->object.sha1, sizeof(parents->item->object.sha1))) + return 1; + } + return 0; +} + +// +// Pushes an item onto the merge order stack. If the top of the stack is +// marked as being a possible "break", we check to see whether it actually +// is a break. +// +static void push_onto_merge_order_stack(struct commit_list **stack, struct commit *item) +{ + struct commit_list *top = *stack; + if (top && (top->item->object.flags & DISCONTINUITY)) { + if (is_parent_of(top->item, item)) { + top->item->object.flags &= ~DISCONTINUITY; + } + } + commit_list_insert(item, stack); +} + +// +// Marks all interesting, visited commits reachable from this commit +// as uninteresting. We stop recursing when we reach the epoch boundary, +// an unvisited node or a node that has already been marking uninteresting. +// This doesn't actually mark all ancestors between the start node and the +// epoch boundary uninteresting, but does ensure that they will +// eventually be marked uninteresting when the main sort_first_epoch +// traversal eventually reaches them. +// +static void mark_ancestors_uninteresting(struct commit *commit) +{ + unsigned int flags = commit->object.flags; + int visited = flags & VISITED; + int boundary = flags & BOUNDARY; + int uninteresting = flags & UNINTERESTING; + + if (uninteresting || boundary || !visited) { + commit->object.flags |= UNINTERESTING; + return; + + // we only need to recurse if + // we are not on the boundary, and, + // we have not already been marked uninteresting, and, + // we have already been visited. + + // + // the main sort_first_epoch traverse will + // mark unreachable all uninteresting, unvisited parents + // as they are visited so there is no need to duplicate + // that traversal here. + // + // similarly, if we are already marked uninteresting + // then either all ancestors have already been marked + // uninteresting or will be once the sort_first_epoch + // traverse reaches them. + // + } + + struct commit_list *next; + + for (next = commit->parents; next; next = next->next) + mark_ancestors_uninteresting(next->item); +} + +// +// Sorts the nodes of the first epoch of the epoch sequence of the epoch headed at head +// into merge order. +// +static void sort_first_epoch(struct commit *head, struct commit_list **stack) +{ + struct commit_list *parents; + struct commit_list *reversed_parents = NULL; + + head->object.flags |= VISITED; + + // + // parse_commit builds the parent list in reverse order with respect to the order of + // the git-commit-tree arguments. + // + // so we need to reverse this list to output the oldest (or most "local") commits last. + // + + for (parents = head->parents; parents; parents = parents->next) + commit_list_insert(parents->item, &reversed_parents); + + // + // todo: by sorting the parents in a different order, we can alter the + // merge order to show contemporaneous changes in parallel branches + // occurring after "local" changes. This is useful for a developer + // when a developer wants to see all changes that were incorporated + // into the same merge as her own changes occur after her own + // changes. + // + + while (reversed_parents) { + + struct commit *parent = pop_commit(&reversed_parents); + + if (head->object.flags & UNINTERESTING) { + // propagates the uninteresting bit to + // all parents. if we have already visited + // this parent, then the uninteresting bit + // will be propagated to each reachable + // commit that is still not marked uninteresting + // and won't otherwise be reached. + mark_ancestors_uninteresting(parent); + } + + if (!(parent->object.flags & VISITED)) { + if (parent->object.flags & BOUNDARY) { + + if (*stack) { + die("something else is on the stack - %s\n", sha1_to_hex((*stack)->item->object.sha1)); + } + + push_onto_merge_order_stack(stack, parent); + parent->object.flags |= VISITED; + + } else { + + sort_first_epoch(parent, stack); + + if (reversed_parents) { + // + // this indicates a possible discontinuity + // it may not be be actual discontinuity if + // the head of parent N happens to be the tail + // of parent N+1 + // + // the next push onto the stack will resolve the + // question + // + (*stack)->item->object.flags |= DISCONTINUITY; + } + } + } + } + + push_onto_merge_order_stack(stack, head); +} + +// +// Emit the contents of the stack. +// +// The stack is freed and replaced by NULL. +// +// Sets the return value to STOP if no further output should be generated. +// +static int emit_stack(struct commit_list **stack, emitter_func emitter) +{ + unsigned int seen = 0; + int action = CONTINUE; + + while (*stack && (action != STOP)) { + + struct commit *next = pop_commit(stack); + + seen |= next->object.flags; + + if (*stack) { + action = (*emitter) (next); + } + } + + if (*stack) { + free_commit_list(*stack); + *stack = NULL; + } + + return (action == STOP || (seen & UNINTERESTING)) ? STOP : CONTINUE; +} + +// +// Sorts an arbitrary epoch into merge order by sorting each epoch +// of its epoch sequence into order. +// +// Note: this algorithm currently leaves traces of its execution in the +// object flags of nodes it discovers. This should probably be fixed. +// +static int sort_in_merge_order(struct commit *head_of_epoch, emitter_func emitter) +{ + struct commit *next = head_of_epoch; + int ret = 0; + int action = CONTINUE; + + ret = parse_commit(head_of_epoch); + + while (next && next->parents && !ret && (action != STOP)) { + + struct commit *base = NULL; + + if ((ret = find_next_epoch_boundary(next, &base))) + return ret; + + next->object.flags |= BOUNDARY; + if (base) { + base->object.flags |= BOUNDARY; + } + + if (HAS_EXACTLY_ONE_PARENT(next)) { + + while (HAS_EXACTLY_ONE_PARENT(next) + && (action != STOP) + && !ret) { + + if (next->object.flags & UNINTERESTING) { + action = STOP; + } else { + action = (*emitter) (next); + } + + if (action != STOP) { + next = next->parents->item; + ret = parse_commit(next); + } + } + + } else { + + struct commit_list *stack = NULL; + sort_first_epoch(next, &stack); + action = emit_stack(&stack, emitter); + next = base; + + } + + } + + if (next && (action != STOP) && !ret) { + (*emitter) (next); + } + + return ret; +} + +// +// Sorts the nodes reachable from a starting list in merge order, we +// first find the base for the starting list and then sort all nodes in this +// subgraph using the sort_first_epoch algorithm. Once we have reached the base +// we can continue sorting using sort_in_merge_order. +// +int sort_list_in_merge_order(struct commit_list *list, emitter_func emitter) +{ + struct commit_list *stack = NULL; + struct commit *base; + + int ret = 0; + int action = CONTINUE; + + struct commit_list *reversed = NULL; + + for (; list; list = list->next) { + + struct commit *next = list->item; + + if (!(next->object.flags & UNINTERESTING)) { + if (next->object.flags & DUPCHECK) { + fprintf(stderr, "%s: duplicate commit %s ignored\n", __FUNCTION__, sha1_to_hex(next->object.sha1)); + } else { + next->object.flags |= DUPCHECK; + commit_list_insert(list->item, &reversed); + } + } + } + + if (!reversed->next) { + + // if there is only one element in the list, we can sort it using + // sort_in_merge_order. + + base = reversed->item; + + } else { + + // otherwise, we search for the base of the list + + if ((ret = find_base_for_list(reversed, &base))) + return ret; + + if (base) { + base->object.flags |= BOUNDARY; + } + + while (reversed) { + sort_first_epoch(pop_commit(&reversed), &stack); + if (reversed) { + // + // if we have more commits to push, then the + // first push for the next parent may (or may not) + // represent a discontinuity with respect to the + // parent currently on the top of the stack. + // + // mark it for checking here, and check it + // with the next push...see sort_first_epoch for + // more details. + // + stack->item->object.flags |= DISCONTINUITY; + } + } + + action = emit_stack(&stack, emitter); + } + + if (base && (action != STOP)) { + ret = sort_in_merge_order(base, emitter); + } + + return ret; +} diff --git a/epoch.h b/epoch.h new file mode 100644 index 0000000000..585110bdd6 --- /dev/null +++ b/epoch.h @@ -0,0 +1,20 @@ +#ifndef EPOCH_H +#define EPOCH_H + + +// return codes for emitter_func +#define STOP 0 +#define CONTINUE 1 +#define DO 2 +typedef int (*emitter_func) (struct commit *); + +int sort_list_in_merge_order(struct commit_list *list, emitter_func emitter); + +#define UNINTERESTING (1u<<2) +#define BOUNDARY (1u<<3) +#define VISITED (1u<<4) +#define DISCONTINUITY (1u<<5) +#define DUPCHECK (1u<<6) + + +#endif /* EPOCH_H */ diff --git a/object.h b/object.h index 464bb0a292..cde8471b56 100644 --- a/object.h +++ b/object.h @@ -15,6 +15,7 @@ struct object { const char *type; struct object_list *refs; struct object_list *attached_deltas; + void *util; }; extern int nr_objs; diff --git a/rev-list.c b/rev-list.c index 2b098c1e88..c27b138f3a 100644 --- a/rev-list.c +++ b/rev-list.c @@ -1,9 +1,9 @@ #include "cache.h" #include "commit.h" +#include "epoch.h" #define SEEN (1u << 0) #define INTERESTING (1u << 1) -#define UNINTERESTING (1u << 2) static const char rev_list_usage[] = "usage: git-rev-list [OPTION] commit-id \n" @@ -11,7 +11,8 @@ static const char rev_list_usage[] = " --max-age=epoch\n" " --min-age=epoch\n" " --header\n" - " --pretty"; + " --pretty\n" + " --merge-order [ --show-breaks ]"; static int verbose_header = 0; static int show_parents = 0; @@ -21,9 +22,19 @@ static unsigned long max_age = -1; static unsigned long min_age = -1; static int max_count = -1; static enum cmit_fmt commit_format = CMIT_FMT_RAW; +static int merge_order = 0; +static int show_breaks = 0; static void show_commit(struct commit *commit) { + if (show_breaks) { + prefix = "| "; + if (commit->object.flags & DISCONTINUITY) { + prefix = "^ "; + } else if (commit->object.flags & BOUNDARY) { + prefix = "= "; + } + } printf("%s%s", prefix, sha1_to_hex(commit->object.sha1)); if (show_parents) { struct commit_list *parents = commit->parents; @@ -37,7 +48,38 @@ static void show_commit(struct commit *commit) static char pretty_header[16384]; pretty_print_commit(commit_format, commit->buffer, ~0, pretty_header, sizeof(pretty_header)); printf("%s%c", pretty_header, hdr_termination); + } +} + +static int filter_commit(struct commit * commit) +{ + if (commit->object.flags & UNINTERESTING) + return CONTINUE; + if (min_age != -1 && (commit->date > min_age)) + return CONTINUE; + if (max_age != -1 && (commit->date < max_age)) + return STOP; + if (max_count != -1 && !max_count--) + return STOP; + + return DO; +} + +static int process_commit(struct commit * commit) +{ + int action=filter_commit(commit); + + if (action == STOP) { + return STOP; } + + if (action == CONTINUE) { + return CONTINUE; + } + + show_commit(commit); + + return CONTINUE; } static void show_commit_list(struct commit_list *list) @@ -45,15 +87,8 @@ static void show_commit_list(struct commit_list *list) while (list) { struct commit *commit = pop_most_recent_commit(&list, SEEN); - if (commit->object.flags & UNINTERESTING) - continue; - if (min_age != -1 && (commit->date > min_age)) - continue; - if (max_age != -1 && (commit->date < max_age)) + if (process_commit(commit) == STOP) break; - if (max_count != -1 && !max_count--) - break; - show_commit(commit); } } @@ -151,6 +186,14 @@ int main(int argc, char **argv) show_parents = 1; continue; } + if (!strncmp(arg, "--merge-order", 13)) { + merge_order = 1; + continue; + } + if (!strncmp(arg, "--show-breaks", 13)) { + show_breaks = 1; + continue; + } flags = 0; if (*arg == '^') { @@ -158,7 +201,7 @@ int main(int argc, char **argv) arg++; limited = 1; } - if (get_sha1(arg, sha1)) + if (get_sha1(arg, sha1) || (show_breaks && !merge_order)) usage(rev_list_usage); commit = lookup_commit_reference(sha1); if (!commit || parse_commit(commit) < 0) @@ -170,9 +213,19 @@ int main(int argc, char **argv) if (!list) usage(rev_list_usage); - if (limited) - list = limit_list(list); + if (!merge_order) { + + if (limited) + list = limit_list(list); + show_commit_list(list); + + } else { + + if (sort_list_in_merge_order(list, &process_commit)) { + die("merge order sort failed\n"); + } + + } - show_commit_list(list); return 0; }