From: Stefan Xenos <sxenos@xxxxxxxxxx>
A change table stores a list of changes, and supports efficient lookup
from a commit hash to the list of changes that reference that commit
directly.
It can be used to look up content commits or metacommits at the head
of a change, but does not support lookup of commits referenced as part
of the commit history.
---
Makefile | 1 +
change-table.c | 207 +++++++++++++++++++++++++++++++++++++++++++++++++
change-table.h | 138 +++++++++++++++++++++++++++++++++
3 files changed, 346 insertions(+)
create mode 100644 change-table.c
create mode 100644 change-table.h
diff --git a/Makefile b/Makefile
index 7ffc383f2b..09cfd3ef1b 100644
--- a/Makefile
+++ b/Makefile
@@ -844,6 +844,7 @@ LIB_OBJS += branch.o
LIB_OBJS += bulk-checkin.o
LIB_OBJS += bundle.o
LIB_OBJS += cache-tree.o
+LIB_OBJS += change-table.o
LIB_OBJS += chdir-notify.o
LIB_OBJS += checkout.o
LIB_OBJS += color.o
diff --git a/change-table.c b/change-table.c
new file mode 100644
index 0000000000..6daff5f58c
--- /dev/null
+++ b/change-table.c
@@ -0,0 +1,207 @@
+#include "cache.h"
+#include "change-table.h"
+#include "commit.h"
+#include "ref-filter.h"
+#include "metacommit-parser.h"
+
+void change_table_init(struct change_table *to_initialize)
+{
+ memset(to_initialize, 0, sizeof(*to_initialize));
+ mem_pool_init(&(to_initialize->memory_pool), 0);
+ to_initialize->memory_pool->block_alloc = 4*1024 - sizeof(struct mp_block);
+ oidmap_init(&(to_initialize->oid_to_metadata_index), 0);
+ string_list_init(&(to_initialize->refname_to_change_head), 1);
+}
+
+static void change_list_clear(struct change_list *to_clear) {
+ string_list_clear(&to_clear->additional_refnames, 0);
+}
+
+static void commit_change_list_entry_clear(
+ struct commit_change_list_entry *to_clear) {
+ change_list_clear(&(to_clear->changes));
+}
+
+static void change_head_array_clear(struct change_head_array *to_clear)
+{
+ FREE_AND_NULL(to_clear->array);
+}
+
+void change_table_clear(struct change_table *to_clear)
+{
+ struct oidmap_iter iter;
+ struct commit_change_list_entry *next;
+ for (next = oidmap_iter_first(&to_clear->oid_to_metadata_index, &iter);
+ next;
+ next = oidmap_iter_next(&iter)) {
+
+ commit_change_list_entry_clear(next);
+ }
+
+ oidmap_free(&to_clear->oid_to_metadata_index, 0);
+ string_list_clear(&(to_clear->refname_to_change_head), 0);
+ change_head_array_clear(&to_clear->heads);
+ mem_pool_discard(to_clear->memory_pool, 0);
+}
+
+/*
+ * Appends a new, empty, change_head struct to the end of the given array.
+ * Returns the index of the newly-added struct.
+ */
+static int change_head_array_append(struct change_head_array *to_add)
+{
+ int index = to_add->nr++;
+ struct change_head *new_head;
+ ALLOC_GROW(to_add->array, to_add->nr, to_add->alloc);
+ new_head = &(to_add->array[index]);
+ memset(new_head, 0, sizeof(*new_head));
+ return index;
+}
+
+static void add_head_to_commit(struct change_table *to_modify,
+ const struct object_id *to_add, const char *refname)
+{
+ struct commit_change_list_entry *entry;
+
+ // Note: the indices in the map are 1-based. 0 is used to indicate a missing
+ // element.
+ entry = oidmap_get(&(to_modify->oid_to_metadata_index), to_add);
+ if (!entry) {
+ entry = mem_pool_calloc(to_modify->memory_pool, 1,
+ sizeof(*entry));
+ oidcpy(&entry->entry.oid, to_add);
+ oidmap_put(&(to_modify->oid_to_metadata_index), entry);
+ string_list_init(&(entry->changes.additional_refnames), 0);
+ }
+
+ if (entry->changes.first_refname == NULL) {
+ entry->changes.first_refname = refname;
+ } else {
+ string_list_insert(&entry->changes.additional_refnames, refname);
+ }
+}
+
+void change_table_add(struct change_table *to_modify, const char *refname,
+ struct commit *to_add)
+{
+ struct change_head *new_head;
+ struct string_list_item *new_item;
+ long index;
+ int metacommit_type;
+
+ index = change_head_array_append(&to_modify->heads);
+ new_head = &(to_modify->heads.array[index]);
+
+ oidcpy(&new_head->head, &(to_add->object.oid));
+
+ metacommit_type = get_metacommit_content(to_add, &new_head->content);
+ if (metacommit_type == METACOMMIT_TYPE_NONE) {
+ oidcpy(&new_head->content, &(to_add->object.oid));
+ }
+ new_head->abandoned = (metacommit_type == METACOMMIT_TYPE_ABANDONED);
+ new_head->remote = starts_with(refname, "refs/remote/");
+ new_head->hidden = starts_with(refname, "refs/hiddenmetas/");
+
+ new_item = string_list_insert(&to_modify->refname_to_change_head, refname);
+ new_item->util = (void*)index;
+ // Use pointers to the copy of the string we're retaining locally
+ refname = new_item->string;
+
+ if (!oideq(&new_head->content, &new_head->head)) {
+ add_head_to_commit(to_modify, &(new_head->content), refname);
+ }
+ add_head_to_commit(to_modify, &(new_head->head), refname);
+}
+
+void change_table_add_all_visible(struct change_table *to_modify,
+ struct repository* repo)
+{
+ struct ref_filter filter;
+ const char *name_patterns[] = {NULL};
+ memset(&filter, 0, sizeof(filter));
+ filter.kind = FILTER_REFS_CHANGES;
+ filter.name_patterns = name_patterns;
+
+ change_table_add_matching_filter(to_modify, repo, &filter);
+}
+
+void change_table_add_matching_filter(struct change_table *to_modify,
+ struct repository* repo, struct ref_filter *filter)
+{
+ struct ref_array matching_refs;
+ int i;
+
+ memset(&matching_refs, 0, sizeof(matching_refs));
+ filter_refs(&matching_refs, filter, filter->kind);
+
+ // Determine the object id for the latest content commit for each change.
+ // Fetch the commit at the head of each change ref. If it's a normal commit,
+ // that's the commit we want. If it's a metacommit, locate its content parent
+ // and use that.
+
+ for (i = 0; i < matching_refs.nr; i++) {
+ struct ref_array_item *item = matching_refs.items[i];
+ struct commit *commit = item->commit;
+
+ commit = lookup_commit_reference_gently(repo, &(item->objectname), 1);
+
+ if (commit != NULL) {
+ change_table_add(to_modify, item->refname, commit);
+ }
+ }
+
+ ref_array_clear(&matching_refs);
+}
+
+static int return_true_callback(const char *refname, void *cb_data)
+{
+ return 1;
+}
+
+int change_table_has_change_referencing(struct change_table *changes,
+ const struct object_id *referenced_commit_id)
+{
+ return for_each_change_referencing(changes, referenced_commit_id,
+ return_true_callback, NULL);
+}
+
+int for_each_change_referencing(struct change_table *table,
+ const struct object_id *referenced_commit_id, each_change_fn fn, void *cb_data)
+{
+ const struct change_list *changes;
+ int i;
+ int retvalue;
+ struct commit_change_list_entry *entry;
+
+ entry = oidmap_get(&table->oid_to_metadata_index,
+ referenced_commit_id);
+ // If this commit isn't referenced by any changes, it won't be in the map
+ if (!entry) {
+ return 0;
+ }
+ changes = &(entry->changes);
+ if (changes->first_refname == NULL) {
+ return 0;
+ }
+ retvalue = fn(changes->first_refname, cb_data);
+ for (i = 0; retvalue == 0 && i < changes->additional_refnames.nr; i++) {
+ retvalue = fn(changes->additional_refnames.items[i].string, cb_data);
+ }
+ return retvalue;
+}
+
+struct change_head* get_change_head(struct change_table *heads,
+ const char* refname)
+{
+ struct string_list_item *item = string_list_lookup(
+ &heads->refname_to_change_head, refname);
+ long index;
+
+ if (!item) {
+ return NULL;
+ }
+
+ index = (long)item->util;
+ return &(heads->heads.array[index]);
+}
+
diff --git a/change-table.h b/change-table.h
new file mode 100644
index 0000000000..7307ae86d0
--- /dev/null
+++ b/change-table.h
@@ -0,0 +1,138 @@
+#ifndef CHANGE_TABLE_H
+#define CHANGE_TABLE_H
+
+#include "oidmap.h"
+
+struct commit;
+struct ref_filter;
+
+/*
+ * This struct holds a list of change refs. The first element is stored inline,
+ * to optimize for small lists.
+ */
+struct change_list {
+ /* Ref name for the first change in the list, or null if none.
+ *
+ * This field is private. Use for_each_change_in to read.
+ */
+ const char* first_refname;
+ /* List of additional change refs. Note that this is empty if the list
+ * contains 0 or 1 elements.
+ *
+ * This field is private. Use for_each_change_in to read.
+ */
+ struct string_list additional_refnames;
+};
+
+/*
+ * Holds information about the head of a single change.
+ */
+struct change_head {
+ /*
+ * The location pointed to by the head of the change. May be a commit or a
+ * metacommit.
+ */
+ struct object_id head;
+ /*
+ * The content commit for the latest commit in the change. Always points to a
+ * real commit, never a metacommit.
+ */
+ struct object_id content;
+ /*
+ * Abandoned: indicates that the content commit should be removed from the
+ * history.
+ *
+ * Hidden: indicates that the change is an inactive change from the
+ * hiddenmetas namespace. Such changes will be hidden from the user by
+ * default.
+ *
+ * Deleted: indicates that the change has been removed from the repository.
+ * That is the ref was deleted since the time this struct was created. Such
+ * entries should be ignored.
+ */
+ int abandoned:1,
+ hidden:1,
+ remote:1,
+ deleted:1;
+};
+
+/*
+ * An array of change_head.
+ */
+struct change_head_array {
+ struct change_head* array;
+ int nr;
+ int alloc;
+};
+
+/*
+ * Holds the list of change refs whose content points to a particular content
+ * commit.
+ */
+struct commit_change_list_entry {
+ struct oidmap_entry entry;
+ struct change_list changes;
+};
+
+/*
+ * Holds information about the heads of each change, and permits effecient
+ * lookup from a commit to the changes that reference it directly.
+ *
+ * All fields should be considered private. Use the change_table functions
+ * to interact with this struct.
+ */
+struct change_table {
+ /**
+ * Memory pool for the objects allocated by the change table.
+ */
+ struct mem_pool *memory_pool;
+ /* Map object_id to commit_change_list_entry structs. */
+ struct oidmap oid_to_metadata_index;
+ /* List of ref names. The util value is an int index into change_metadata
+ * array.
+ */
+ struct string_list refname_to_change_head;
+ /* change_head structures for each head */
+ struct change_head_array heads;
+};
+
+extern void change_table_init(struct change_table *to_initialize);
+extern void change_table_clear(struct change_table *to_clear);
+
+/* Adds the given change head to the change_table struct */
+extern void change_table_add(struct change_table *to_modify,
+ const char *refname, struct commit *target);
+
+/* Adds the non-hidden local changes to the given change_table struct.
+ */
+extern void change_table_add_all_visible(struct change_table *to_modify,
+ struct repository *repo);
+
+/*
+ * Adds all changes matching the given ref filter to the given change_table
+ * struct.
+ */
+extern void change_table_add_matching_filter(struct change_table *to_modify,
+ struct repository* repo, struct ref_filter *filter);
+
+typedef int each_change_fn(const char *refname, void *cb_data);
+
+extern int change_table_has_change_referencing(struct change_table *changes,
+ const struct object_id *referenced_commit_id);
+
+/* Iterates over all changes that reference the given commit. For metacommits,
+ * this is the list of changes that point directly to that metacommit.
+ * For normal commits, this is the list of changes that have this commit as
+ * their latest content.
+ */
+extern int for_each_change_referencing(struct change_table *heads,
+ const struct object_id *referenced_commit_id, each_change_fn fn, void *cb_data);
+
+/**
+ * Returns the change head for the given refname. Returns NULL if no such change
+ * exists.
+ */
+extern struct change_head* get_change_head(struct change_table *heads,
+ const char* refname);
+
+#endif
--
2.20.1.321.g9e740568ce-goog
