[PATCH 03/13] gc: make gc_consumer and gc_state structs transparent

[Vladimir Davydov <vdavydov.dev@gmail.com>]

It's exasperating to write trivial external functions for each member of
an opaque struct (gc_consumer_vclock, gc_consumer_name, etc) while we
could simply access those fields directly if we made those structs
transparent. Since we usually define structs as transparent if we need
to use them outside a source file, let's do the same for gc_consumer and
gc_state and remove all those one-line wrappers.
---
 src/box/box.cc     |  2 +-
 src/box/gc.c       | 63 +-----------------------------------------------------
 src/box/gc.h       | 63 ++++++++++++++++++++++++++++++++++++------------------
 src/box/lua/info.c |  4 ++--
 4 files changed, 46 insertions(+), 86 deletions(-)

diff --git a/src/box/box.cc b/src/box/box.cc
index 804fc00e..207e411c 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1613,7 +1613,7 @@ box_process_vote(struct ballot *ballot)
 {
 	ballot->is_ro = cfg_geti("read_only") != 0;
 	vclock_copy(&ballot->vclock, &replicaset.vclock);
-	gc_vclock(&ballot->gc_vclock);
+	vclock_copy(&ballot->gc_vclock, &gc.wal_vclock);
 }
 
 /** Insert a new cluster into _schema */
diff --git a/src/box/gc.c b/src/box/gc.c
index 3ab76626..a45806b6 100644
--- a/src/box/gc.c
+++ b/src/box/gc.c
@@ -48,44 +48,7 @@
 #include "engine.h"		/* engine_collect_garbage() */
 #include "wal.h"		/* wal_collect_garbage() */
 
-typedef rb_node(struct gc_consumer) gc_node_t;
-
-/**
- * The object of this type is used to prevent garbage
- * collection from removing files that are still in use.
- */
-struct gc_consumer {
-	/** Link in gc_state::consumers. */
-	gc_node_t node;
-	/** Human-readable name. */
-	char *name;
-	/** The vclock tracked by this consumer. */
-	struct vclock vclock;
-	/** Consumer type, indicating that consumer only consumes
-	 * WAL files, or both - SNAP and WAL.
-	 */
-	enum gc_consumer_type type;
-};
-
-typedef rb_tree(struct gc_consumer) gc_tree_t;
-
-/** Garbage collection state. */
-struct gc_state {
-	/** Number of checkpoints to maintain. */
-	int checkpoint_count;
-	/** Max vclock WAL garbage collection has been called for. */
-	struct vclock wal_vclock;
-	/** Max vclock checkpoint garbage collection has been called for. */
-	struct vclock checkpoint_vclock;
-	/** Registered consumers, linked by gc_consumer::node. */
-	gc_tree_t consumers;
-	/**
-	 * Latch serializing concurrent invocations of engine
-	 * garbage collection callbacks.
-	 */
-	struct latch latch;
-};
-static struct gc_state gc;
+struct gc_state gc;
 
 /**
  * Comparator used for ordering gc_consumer objects by signature
@@ -163,12 +126,6 @@ gc_free(void)
 	}
 }
 
-void
-gc_vclock(struct vclock *vclock)
-{
-	vclock_copy(vclock, &gc.wal_vclock);
-}
-
 /** Find the consumer that uses the oldest checkpoint. */
 struct gc_consumer *
 gc_tree_first_checkpoint(gc_tree_t *consumers)
@@ -321,24 +278,6 @@ gc_consumer_advance(struct gc_consumer *consumer, const struct vclock *vclock)
 		gc_run();
 }
 
-const char *
-gc_consumer_name(const struct gc_consumer *consumer)
-{
-	return consumer->name;
-}
-
-void
-gc_consumer_vclock(const struct gc_consumer *consumer, struct vclock *vclock)
-{
-	vclock_copy(vclock, &consumer->vclock);
-}
-
-int64_t
-gc_consumer_signature(const struct gc_consumer *consumer)
-{
-	return vclock_sum(&consumer->vclock);
-}
-
 struct gc_consumer *
 gc_consumer_iterator_next(struct gc_consumer_iterator *it)
 {
diff --git a/src/box/gc.h b/src/box/gc.h
index 36a951bf..2c03770d 100644
--- a/src/box/gc.h
+++ b/src/box/gc.h
@@ -32,13 +32,14 @@
  */
 
 #include <stddef.h>
-#include <stdint.h>
+
+#include "vclock.h"
+#include "latch.h"
 
 #if defined(__cplusplus)
 extern "C" {
 #endif /* defined(__cplusplus) */
 
-struct vclock;
 struct gc_consumer;
 
 /** Consumer type: WAL consumer, or SNAP */
@@ -48,6 +49,45 @@ enum gc_consumer_type {
 	GC_CONSUMER_ALL = 3,
 };
 
+typedef rb_node(struct gc_consumer) gc_node_t;
+
+/**
+ * The object of this type is used to prevent garbage
+ * collection from removing files that are still in use.
+ */
+struct gc_consumer {
+	/** Link in gc_state::consumers. */
+	gc_node_t node;
+	/** Human-readable name. */
+	char *name;
+	/** The vclock tracked by this consumer. */
+	struct vclock vclock;
+	/** Consumer type, indicating that consumer only consumes
+	 * WAL files, or both - SNAP and WAL.
+	 */
+	enum gc_consumer_type type;
+};
+
+typedef rb_tree(struct gc_consumer) gc_tree_t;
+
+/** Garbage collection state. */
+struct gc_state {
+	/** Number of checkpoints to maintain. */
+	int checkpoint_count;
+	/** Max vclock WAL garbage collection has been called for. */
+	struct vclock wal_vclock;
+	/** Max vclock checkpoint garbage collection has been called for. */
+	struct vclock checkpoint_vclock;
+	/** Registered consumers, linked by gc_consumer::node. */
+	gc_tree_t consumers;
+	/**
+	 * Latch serializing concurrent invocations of engine
+	 * garbage collection callbacks.
+	 */
+	struct latch latch;
+};
+extern struct gc_state gc;
+
 /**
  * Initialize the garbage collection state.
  */
@@ -61,12 +101,6 @@ void
 gc_free(void);
 
 /**
- * Get the oldest available vclock.
- */
-void
-gc_vclock(struct vclock *vclock);
-
-/**
  * Invoke garbage collection in order to remove files left
  * from old checkpoints. The number of checkpoints saved by
  * this function is specified by box.cfg.checkpoint_count.
@@ -112,19 +146,6 @@ gc_consumer_unregister(struct gc_consumer *consumer);
 void
 gc_consumer_advance(struct gc_consumer *consumer, const struct vclock *vclock);
 
-/** Return the name of a consumer. */
-const char *
-gc_consumer_name(const struct gc_consumer *consumer);
-
-/** Return the vclock a consumer tracks. */
-void
-gc_consumer_vclock(const struct gc_consumer *consumer, struct vclock *vclock);
-
-
-/** Return the vclock signature a consumer tracks. */
-int64_t
-gc_consumer_signature(const struct gc_consumer *consumer);
-
 /**
  * Iterator over registered consumers. The iterator is valid
  * as long as the caller doesn't yield.
diff --git a/src/box/lua/info.c b/src/box/lua/info.c
index d9ea73a6..85b21c65 100644
--- a/src/box/lua/info.c
+++ b/src/box/lua/info.c
@@ -397,11 +397,11 @@ lbox_info_gc_call(struct lua_State *L)
 		lua_createtable(L, 0, 2);
 
 		lua_pushstring(L, "name");
-		lua_pushstring(L, gc_consumer_name(consumer));
+		lua_pushstring(L, consumer->name);
 		lua_settable(L, -3);
 
 		lua_pushstring(L, "signature");
-		luaL_pushint64(L, gc_consumer_signature(consumer));
+		luaL_pushint64(L, vclock_sum(&consumer->vclock));
 		lua_settable(L, -3);
 
 		lua_rawseti(L, -2, ++count);
-- 
2.11.0