[PATCH v4 02/13] bulk-checkin: rebrand plug/unplug APIs as 'odb transactions'

["Neeraj Singh via GitGitGadget" <gitgitgadget@gmail.com>]

From: Neeraj Singh <neerajsi@microsoft.com>

Make it clearer in the naming and documentation of the plug_bulk_checkin
and unplug_bulk_checkin APIs that they can be thought of as
a "transaction" to optimize operations on the object database. These
transactions may be nested so that subsystems like the cache-tree
writing code can optimize their operations without caring whether the
top-level code has a transaction active.

Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
---
 builtin/add.c  |  4 ++--
 bulk-checkin.c | 20 ++++++++++++--------
 bulk-checkin.h | 14 ++++++++++++--
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/builtin/add.c b/builtin/add.c
index 3ffb86a4338..9bf37ceae8e 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -670,7 +670,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 		string_list_clear(&only_match_skip_worktree, 0);
 	}
 
-	plug_bulk_checkin();
+	begin_odb_transaction();
 
 	if (add_renormalize)
 		exit_status |= renormalize_tracked_files(&pathspec, flags);
@@ -682,7 +682,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	if (chmod_arg && pathspec.nr)
 		exit_status |= chmod_pathspec(&pathspec, chmod_arg[0], show_only);
-	unplug_bulk_checkin();
+	end_odb_transaction();
 
 finish:
 	if (write_locked_index(&the_index, &lock_file,
diff --git a/bulk-checkin.c b/bulk-checkin.c
index 577b135e39c..8b0fd5c7723 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -10,7 +10,7 @@
 #include "packfile.h"
 #include "object-store.h"
 
-static int bulk_checkin_plugged;
+static int odb_transaction_nesting;
 
 static struct bulk_checkin_state {
 	char *pack_tmp_name;
@@ -280,21 +280,25 @@ int index_bulk_checkin(struct object_id *oid,
 {
 	int status = deflate_to_pack(&bulk_checkin_state, oid, fd, size, type,
 				     path, flags);
-	if (!bulk_checkin_plugged)
+	if (!odb_transaction_nesting)
 		finish_bulk_checkin(&bulk_checkin_state);
 	return status;
 }
 
-void plug_bulk_checkin(void)
+void begin_odb_transaction(void)
 {
-	assert(!bulk_checkin_plugged);
-	bulk_checkin_plugged = 1;
+	odb_transaction_nesting += 1;
 }
 
-void unplug_bulk_checkin(void)
+void end_odb_transaction(void)
 {
-	assert(bulk_checkin_plugged);
-	bulk_checkin_plugged = 0;
+	odb_transaction_nesting -= 1;
+	if (odb_transaction_nesting < 0)
+		BUG("Unbalanced ODB transaction nesting");
+
+	if (odb_transaction_nesting)
+		return;
+
 	if (bulk_checkin_state.f)
 		finish_bulk_checkin(&bulk_checkin_state);
 }
diff --git a/bulk-checkin.h b/bulk-checkin.h
index b26f3dc3b74..69a94422ac7 100644
--- a/bulk-checkin.h
+++ b/bulk-checkin.h
@@ -10,7 +10,17 @@ int index_bulk_checkin(struct object_id *oid,
 		       int fd, size_t size, enum object_type type,
 		       const char *path, unsigned flags);
 
-void plug_bulk_checkin(void);
-void unplug_bulk_checkin(void);
+/*
+ * Tell the object database to optimize for adding
+ * multiple objects. end_odb_transaction must be called
+ * to make new objects visible.
+ */
+void begin_odb_transaction(void);
+
+/*
+ * Tell the object database to make any objects from the
+ * current transaction visible.
+ */
+void end_odb_transaction(void);
 
 #endif
-- 
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