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[PATCH v3 18/44] refs: move transaction functions into common code

From
David Turner <dturner@twopensource.com>
Date
Oct 12, 2015, 21:51 UTC
Message-ID
<1444686725-27660-19-git-send-email-dturner@twopensource.com>
In-Reply-To
<1444686725-27660-1-git-send-email-dturner@twopensource.com>

The common ref code will build up a ref transaction. Backends will then commit it. So the transaction creation and update functions should be in the common code. We also need to move the ref structs into the common code so that alternate backends can access them.

Later, we will modify struct ref_update to support alternate backends.
Signed-off-by: David Turner <dturner@twopensource.com>
---
 refs-be-files.c | 198 --------------------------------------------------------
 refs.c          | 108 +++++++++++++++++++++++++++++++
 refs.h          |  91 +++++++++++++++++++++++++-
 3 files changed, 198 insertions(+), 199 deletions(-)
diff --git a/refs-be-files.c b/refs-be-files.c
index 34ed220..1308955 100644
--- a/refs-be-files.c
+++ b/refs-be-files.c
@@ -13,41 +13,6 @@ struct ref_lock {
 	struct object_id old_oid;
 };
 
-/*
- * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
- * refs (i.e., because the reference is about to be deleted anyway).
- */
-#define REF_DELETING	0x02
-
-/*
- * Used as a flag in ref_update::flags when a loose ref is being
- * pruned.
- */
-#define REF_ISPRUNING	0x04
-
-/*
- * Used as a flag in ref_update::flags when the reference should be
- * updated to new_sha1.
- */
-#define REF_HAVE_NEW	0x08
-
-/*
- * Used as a flag in ref_update::flags when old_sha1 should be
- * checked.
- */
-#define REF_HAVE_OLD	0x10
-
-/*
- * Used as a flag in ref_update::flags when the lockfile needs to be
- * committed.
- */
-#define REF_NEEDS_COMMIT 0x20
-
-/*
- * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
- * value to ref_update::flags
- */
-
 struct ref_entry;
 
 /*
@@ -3243,169 +3208,6 @@ int for_each_reflog(each_ref_fn fn, void *cb_data)
 	return retval;
 }
 
-/**
- * Information needed for a single ref update. Set new_sha1 to the new
- * value or to null_sha1 to delete the ref. To check the old value
- * while the ref is locked, set (flags & REF_HAVE_OLD) and set
- * old_sha1 to the old value, or to null_sha1 to ensure the ref does
- * not exist before update.
- */
-struct ref_update {
-	/*
-	 * If (flags & REF_HAVE_NEW), set the reference to this value:
-	 */
-	unsigned char new_sha1[20];
-	/*
-	 * If (flags & REF_HAVE_OLD), check that the reference
-	 * previously had this value:
-	 */
-	unsigned char old_sha1[20];
-	/*
-	 * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
-	 * REF_DELETING, and REF_ISPRUNING:
-	 */
-	unsigned int flags;
-	struct ref_lock *lock;
-	int type;
-	char *msg;
-	const char refname[FLEX_ARRAY];
-};
-
-/*
- * Transaction states.
- * OPEN:   The transaction is in a valid state and can accept new updates.
- *         An OPEN transaction can be committed.
- * CLOSED: A closed transaction is no longer active and no other operations
- *         than free can be used on it in this state.
- *         A transaction can either become closed by successfully committing
- *         an active transaction or if there is a failure while building
- *         the transaction thus rendering it failed/inactive.
- */
-enum ref_transaction_state {
-	REF_TRANSACTION_OPEN   = 0,
-	REF_TRANSACTION_CLOSED = 1
-};
-
-/*
- * Data structure for holding a reference transaction, which can
- * consist of checks and updates to multiple references, carried out
- * as atomically as possible.  This structure is opaque to callers.
- */
-struct ref_transaction {
-	struct ref_update **updates;
-	size_t alloc;
-	size_t nr;
-	enum ref_transaction_state state;
-};
-
-struct ref_transaction *ref_transaction_begin(struct strbuf *err)
-{
-	assert(err);
-
-	return xcalloc(1, sizeof(struct ref_transaction));
-}
-
-void ref_transaction_free(struct ref_transaction *transaction)
-{
-	int i;
-
-	if (!transaction)
-		return;
-
-	for (i = 0; i < transaction->nr; i++) {
-		free(transaction->updates[i]->msg);
-		free(transaction->updates[i]);
-	}
-	free(transaction->updates);
-	free(transaction);
-}
-
-static struct ref_update *add_update(struct ref_transaction *transaction,
-				     const char *refname)
-{
-	size_t len = strlen(refname) + 1;
-	struct ref_update *update = xcalloc(1, sizeof(*update) + len);
-
-	memcpy((char *)update->refname, refname, len); /* includes NUL */
-	ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
-	transaction->updates[transaction->nr++] = update;
-	return update;
-}
-
-int ref_transaction_update(struct ref_transaction *transaction,
-			   const char *refname,
-			   const unsigned char *new_sha1,
-			   const unsigned char *old_sha1,
-			   unsigned int flags, const char *msg,
-			   struct strbuf *err)
-{
-	struct ref_update *update;
-
-	assert(err);
-
-	if (transaction->state != REF_TRANSACTION_OPEN)
-		die("BUG: update called for transaction that is not open");
-
-	if (new_sha1 && !is_null_sha1(new_sha1) &&
-	    check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
-		strbuf_addf(err, "refusing to update ref with bad name %s",
-			    refname);
-		return -1;
-	}
-
-	update = add_update(transaction, refname);
-	if (new_sha1) {
-		hashcpy(update->new_sha1, new_sha1);
-		flags |= REF_HAVE_NEW;
-	}
-	if (old_sha1) {
-		hashcpy(update->old_sha1, old_sha1);
-		flags |= REF_HAVE_OLD;
-	}
-	update->flags = flags;
-	if (msg)
-		update->msg = xstrdup(msg);
-	return 0;
-}
-
-int ref_transaction_create(struct ref_transaction *transaction,
-			   const char *refname,
-			   const unsigned char *new_sha1,
-			   unsigned int flags, const char *msg,
-			   struct strbuf *err)
-{
-	if (!new_sha1 || is_null_sha1(new_sha1))
-		die("BUG: create called without valid new_sha1");
-	return ref_transaction_update(transaction, refname, new_sha1,
-				      null_sha1, flags, msg, err);
-}
-
-int ref_transaction_delete(struct ref_transaction *transaction,
-			   const char *refname,
-			   const unsigned char *old_sha1,
-			   unsigned int flags, const char *msg,
-			   struct strbuf *err)
-{
-	if (old_sha1 && is_null_sha1(old_sha1))
-		die("BUG: delete called with old_sha1 set to zeros");
-	return ref_transaction_update(transaction, refname,
-				      null_sha1, old_sha1,
-				      flags, msg, err);
-}
-
-int ref_transaction_verify(struct ref_transaction *transaction,
-			   const char *refname,
-			   const unsigned char *old_sha1,
-			   unsigned int flags,
-			   struct strbuf *err)
-{
-	if (!old_sha1)
-		die("BUG: verify called with old_sha1 set to NULL");
-	return ref_transaction_update(transaction, refname,
-				      NULL, old_sha1,
-				      flags, NULL, err);
-}
-
 static int ref_update_reject_duplicates(struct string_list *refnames,
 					struct strbuf *err)
 {
diff --git a/refs.c b/refs.c
index 0f4e19a..25ad3b5 100644
--- a/refs.c
+++ b/refs.c
@@ -877,3 +877,111 @@ int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 
 	return ret;
 }
+
+struct ref_transaction *ref_transaction_begin(struct strbuf *err)
+{
+	assert(err);
+
+	return xcalloc(1, sizeof(struct ref_transaction));
+}
+
+void ref_transaction_free(struct ref_transaction *transaction)
+{
+	int i;
+
+	if (!transaction)
+		return;
+
+	for (i = 0; i < transaction->nr; i++) {
+		free(transaction->updates[i]->msg);
+		free(transaction->updates[i]);
+	}
+	free(transaction->updates);
+	free(transaction);
+}
+
+static struct ref_update *add_update(struct ref_transaction *transaction,
+				     const char *refname)
+{
+	size_t len = strlen(refname) + 1;
+	struct ref_update *update = xcalloc(1, sizeof(*update) + len);
+
+	memcpy((char *)update->refname, refname, len); /* includes NUL */
+	ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
+	transaction->updates[transaction->nr++] = update;
+	return update;
+}
+
+int ref_transaction_update(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *new_sha1,
+			   const unsigned char *old_sha1,
+			   unsigned int flags, const char *msg,
+			   struct strbuf *err)
+{
+	struct ref_update *update;
+
+	assert(err);
+
+	if (transaction->state != REF_TRANSACTION_OPEN)
+		die("BUG: update called for transaction that is not open");
+
+	if (new_sha1 && !is_null_sha1(new_sha1) &&
+	    check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+		strbuf_addf(err, "refusing to update ref with bad name %s",
+			    refname);
+		return -1;
+	}
+
+	update = add_update(transaction, refname);
+	if (new_sha1) {
+		hashcpy(update->new_sha1, new_sha1);
+		flags |= REF_HAVE_NEW;
+	}
+	if (old_sha1) {
+		hashcpy(update->old_sha1, old_sha1);
+		flags |= REF_HAVE_OLD;
+	}
+	update->flags = flags;
+	if (msg)
+		update->msg = xstrdup(msg);
+	return 0;
+}
+
+int ref_transaction_create(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *new_sha1,
+			   unsigned int flags, const char *msg,
+			   struct strbuf *err)
+{
+	if (!new_sha1 || is_null_sha1(new_sha1))
+		die("BUG: create called without valid new_sha1");
+	return ref_transaction_update(transaction, refname, new_sha1,
+				      null_sha1, flags, msg, err);
+}
+
+int ref_transaction_delete(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *old_sha1,
+			   unsigned int flags, const char *msg,
+			   struct strbuf *err)
+{
+	if (old_sha1 && is_null_sha1(old_sha1))
+		die("BUG: delete called with old_sha1 set to zeros");
+	return ref_transaction_update(transaction, refname,
+				      null_sha1, old_sha1,
+				      flags, msg, err);
+}
+
+int ref_transaction_verify(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *old_sha1,
+			   unsigned int flags,
+			   struct strbuf *err)
+{
+	if (!old_sha1)
+		die("BUG: verify called with old_sha1 set to NULL");
+	return ref_transaction_update(transaction, refname,
+				      NULL, old_sha1,
+				      flags, NULL, err);
+}
diff --git a/refs.h b/refs.h
index 729bc3c..4940ae9 100644
--- a/refs.h
+++ b/refs.h
@@ -94,6 +94,84 @@ extern int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref);
 extern int dwim_log(const char *str, int len, unsigned char *sha1, char **ref);
 
 /*
+ * Transaction states.
+ * OPEN:   The transaction is in a valid state and can accept new updates.
+ *         An OPEN transaction can be committed.
+ * CLOSED: A closed transaction is no longer active and no other operations
+ *         than free can be used on it in this state.
+ *         A transaction can either become closed by successfully committing
+ *         an active transaction or if there is a failure while building
+ *         the transaction thus rendering it failed/inactive.
+ */
+enum ref_transaction_state {
+	REF_TRANSACTION_OPEN   = 0,
+	REF_TRANSACTION_CLOSED = 1
+};
+
+/*
+ * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
+ * refs (i.e., because the reference is about to be deleted anyway).
+ */
+#define REF_DELETING	0x02
+
+/*
+ * Used as a flag in ref_update::flags when a loose ref is being
+ * pruned.
+ */
+#define REF_ISPRUNING	0x04
+
+/*
+ * Used as a flag in ref_update::flags when the reference should be
+ * updated to new_sha1.
+ */
+#define REF_HAVE_NEW	0x08
+
+/*
+ * Used as a flag in ref_update::flags when old_sha1 should be
+ * checked.
+ */
+#define REF_HAVE_OLD	0x10
+
+/*
+ * Used as a flag in ref_update::flags when the lockfile needs to be
+ * committed.
+ */
+#define REF_NEEDS_COMMIT 0x20
+
+/*
+ * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
+ * value to ref_update::flags
+ */
+
+/**
+ * Information needed for a single ref update. Set new_sha1 to the new
+ * value or to null_sha1 to delete the ref. To check the old value
+ * while the ref is locked, set (flags & REF_HAVE_OLD) and set
+ * old_sha1 to the old value, or to null_sha1 to ensure the ref does
+ * not exist before update.
+ */
+struct ref_update {
+	/*
+	 * If (flags & REF_HAVE_NEW), set the reference to this value:
+	 */
+	unsigned char new_sha1[20];
+	/*
+	 * If (flags & REF_HAVE_OLD), check that the reference
+	 * previously had this value:
+	 */
+	unsigned char old_sha1[20];
+	/*
+	 * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
+	 * REF_DELETING, and REF_ISPRUNING:
+	 */
+	unsigned int flags;
+	struct ref_lock *lock;
+	int type;
+	char *msg;
+	const char refname[FLEX_ARRAY];
+};
+
+/*
  * A ref_transaction represents a collection of ref updates
  * that should succeed or fail together.
  *
@@ -125,7 +203,18 @@ extern int dwim_log(const char *str, int len, unsigned char *sha1, char **ref);
  * The message is appended to err without first clearing err.
  * err will not be '\n' terminated.
  */
-struct ref_transaction;
+
+/*
+ * Data structure for holding a reference transaction, which can
+ * consist of checks and updates to multiple references, carried out
+ * as atomically as possible.  This structure is opaque to callers.
+ */
+struct ref_transaction {
+	struct ref_update **updates;
+	size_t alloc;
+	size_t nr;
+	enum ref_transaction_state state;
+};
 
 /*
  * Bit values set in the flags argument passed to each_ref_fn():

-- 
2.4.2.644.g97b850b-twtrsrc
Previous: David TurnerNext: Michael Haggerty
Message 28 of 71 in “alternate refs backends”
  1. 00/44 alternate refs backendsDavid Turner, Oct 12, 2015
  2. 01/44 refs.c: create a public version of verify_refname_availableDavid Turner, Oct 12, 2015
  3. Michael HaggertyOct 13, 2015
  4. 02/44 refs: make repack_without_refs and is_branch publicDavid Turner, Oct 12, 2015
  5. Michael HaggertyOct 13, 2015
  6. Michael HaggertyOct 13, 2015
  7. David TurnerOct 13, 2015
  8. 03/44 refs-be-files.c: rename refs to refs-be-filesDavid Turner, Oct 12, 2015
  9. 04/44 refs.c: add a new refs.c file to hold all common refs codeDavid Turner, Oct 12, 2015
  10. 05/44 refs.c: move update_ref to refs.cDavid Turner, Oct 12, 2015
  11. Michael HaggertyOct 13, 2015
  12. David TurnerOct 13, 2015
  13. David TurnerOct 14, 2015
  14. 06/44 refs.c: move delete_ref and delete_refs to the common codeDavid Turner, Oct 12, 2015
  15. Michael HaggertyOct 13, 2015
  16. 07/44 refs.c: move read_ref_at to the common refs fileDavid Turner, Oct 12, 2015
  17. 08/44 refs.c: move the hidden refs functions to the common codeDavid Turner, Oct 12, 2015
  18. 09/44 refs.c: move dwim and friend functions to the common refs codeDavid Turner, Oct 12, 2015
  19. 10/44 refs.c: move warn_if_dangling_symref* to the common codeDavid Turner, Oct 12, 2015
  20. 11/44 refs.c: move read_ref, read_ref_full and ref_exists to the common codeDavid Turner, Oct 12, 2015
  21. 12/44 refs.c: move resolve_refdup to commonDavid Turner, Oct 12, 2015
  22. 13/44 refs.c: move check_refname_format to the common codeDavid Turner, Oct 12, 2015
  23. 14/44 refs.c: move is_branch to the common codeDavid Turner, Oct 12, 2015
  24. 15/44 refs.c: move prettify_refname to the common codeDavid Turner, Oct 12, 2015
  25. 16/44 refs.c: move ref iterators to the common codeDavid Turner, Oct 12, 2015
  26. Michael HaggertyOct 13, 2015
  27. 17/44 refs.c: move head_ref_namespaced to the common codeDavid Turner, Oct 12, 2015
  28. 18/44 refs: move transaction functions into common codeDavid Turner, Oct 12, 2015
  29. Michael HaggertyOct 13, 2015
  30. Michael HaggertyOct 13, 2015
  31. David TurnerOct 13, 2015
  32. David TurnerOct 13, 2015
  33. 19/44 refs: add a backend method structure with transaction functionsDavid Turner, Oct 12, 2015
  34. 19/44 refs-be-files.c: add a backend method structure with transaction functionsDavid Turner, Oct 12, 2015
  35. David TurnerOct 12, 2015
  36. Michael HaggertyOct 13, 2015
  37. David TurnerOct 13, 2015
  38. Michael HaggertyOct 13, 2015
  39. 20/44 refs-be-files.c: add methods for misc ref operationsDavid Turner, Oct 12, 2015
  40. Michael HaggertyOct 13, 2015
  41. 21/44 refs-be-files.c: add methods for the ref iteratorsDavid Turner, Oct 12, 2015
  42. 22/44 refs-be-files.c: add method for for_each_reftype_...David Turner, Oct 12, 2015
  43. 23/44 refs-be-files.c: add do_for_each_per_worktree_refDavid Turner, Oct 12, 2015
  44. 24/44 refs.c: move refname_is_safe to the common codeDavid Turner, Oct 12, 2015
  45. 25/44 refs.h: document make refname_is_safe and add it to headerDavid Turner, Oct 12, 2015
  46. Michael HaggertyOct 13, 2015
  47. Michael HaggertyOct 13, 2015
  48. David TurnerOct 13, 2015
  49. 26/44 refs.c: move copy_msg to the common codeDavid Turner, Oct 12, 2015
  50. Michael HaggertyOct 13, 2015
  51. 27/44 refs.c: move peel_object to the common codeDavid Turner, Oct 12, 2015
  52. Michael HaggertyOct 13, 2015
  53. 28/44 refs.c: move should_autocreate_reflog to common codeDavid Turner, Oct 12, 2015
  54. 29/44 refs.c: add ref backend init functionDavid Turner, Oct 12, 2015
  55. 30/44 refs.c: add methods for reflogDavid Turner, Oct 12, 2015
  56. 31/44 refs.c: add method for initial ref transaction commitDavid Turner, Oct 12, 2015
  57. 32/44 initdb: move safe_create_dir into common codeDavid Turner, Oct 12, 2015
  58. 33/44 refs.c: add method for initializing refs dbDavid Turner, Oct 12, 2015
  59. 34/44 refs-be-files.c: add method to rename refsDavid Turner, Oct 12, 2015
  60. 35/44 refs: make lock genericDavid Turner, Oct 12, 2015
  61. 36/44 refs: make files_log_ref_write functions publicDavid Turner, Oct 12, 2015
  62. 37/44 refs: break out a ref conflict checkDavid Turner, Oct 12, 2015
  63. Michael HaggertyOct 13, 2015
  64. David TurnerOct 13, 2015
  65. 38/44 refs: move duplicate check to common codeDavid Turner, Oct 12, 2015
  66. 39/44 refs: always handle non-normal refs in files backendDavid Turner, Oct 12, 2015
  67. 40/44 refs: allow ref backend to be set for cloneDavid Turner, Oct 12, 2015
  68. 41/44 refs: add register_refs_backendDavid Turner, Oct 12, 2015
  69. 42/44 introduce "extensions" form of core.repositoryformatversionDavid Turner, Oct 12, 2015
  70. 43/44 refs: add LMDB refs backendDavid Turner, Oct 12, 2015
  71. 44/44 refs: tests for db backendDavid Turner, Oct 12, 2015

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