Implement arena.<i>.destroy .

Add MALLCTL_ARENAS_DESTROYED for accessing destroyed arena stats as an
analogue to MALLCTL_ARENAS_ALL.

This resolves #382.

include/jemalloc/internal/arena.h

@@ -290,6 +290,7 @@ bool	arena_decay_time_set(tsdn_t *tsdn, arena_t *arena, ssize_t decay_time);
 void	arena_purge(tsdn_t *tsdn, arena_t *arena, bool all);
 void	arena_maybe_purge(tsdn_t *tsdn, arena_t *arena);
 void	arena_reset(tsd_t *tsd, arena_t *arena);
+void	arena_destroy(tsd_t *tsd, arena_t *arena);
 void	arena_tcache_fill_small(tsdn_t *tsdn, arena_t *arena,
     tcache_bin_t *tbin, szind_t binind, uint64_t prof_accumbytes);
 void	arena_alloc_junk_small(void *ptr, const arena_bin_info_t *bin_info,

include/jemalloc/internal/ctl.h

@@ -32,7 +32,10 @@ struct ctl_indexed_node_s {
 };
 
 struct ctl_arena_stats_s {
+	unsigned		arena_ind;
 	bool			initialized;
+	ql_elm(ctl_arena_stats_t)	destroyed_link;
+
 	unsigned		nthreads;
 	const char		*dss;
 	ssize_t			decay_time;
@@ -62,7 +65,14 @@ struct ctl_stats_s {
 	size_t			mapped;
 	size_t			retained;
 	unsigned		narenas;
-	ctl_arena_stats_t	*arenas[1 << MALLOCX_ARENA_BITS];
+	ql_head(ctl_arena_stats_t)	destroyed;
+	/*
+	 * Element 0 contains merged stats for extant arenas (accessed via
+	 * MALLCTL_ARENAS_ALL), element 1 contains merged stats for destroyed
+	 * arenas (accessed via MALLCTL_ARENAS_DESTROYED), and the remaining
+	 * MALLOCX_ARENA_MAX+1 elements correspond to arenas.
+	 */
+	ctl_arena_stats_t	*arenas[MALLOCX_ARENA_MAX + 3];
 };
 
 #endif /* JEMALLOC_H_STRUCTS */

include/jemalloc/internal/extent.h

@@ -125,6 +125,8 @@ extent_t	*extent_alloc_wrapper(tsdn_t *tsdn, arena_t *arena,
 void	extent_dalloc_gap(tsdn_t *tsdn, arena_t *arena, extent_t *extent);
 void	extent_dalloc_cache(tsdn_t *tsdn, arena_t *arena,
     extent_hooks_t **r_extent_hooks, extent_t *extent);
+bool	extent_dalloc_wrapper_try(tsdn_t *tsdn, arena_t *arena,
+    extent_hooks_t **r_extent_hooks, extent_t *extent);
 void	extent_dalloc_wrapper(tsdn_t *tsdn, arena_t *arena,
     extent_hooks_t **r_extent_hooks, extent_t *extent);
 bool	extent_commit_wrapper(tsdn_t *tsdn, arena_t *arena,

include/jemalloc/internal/jemalloc_internal.h.in

@@ -215,6 +215,7 @@ typedef unsigned szind_t;
 #define	MALLOCX_TCACHE_SHIFT	8
 #define	MALLOCX_ARENA_MASK \
     (((1 << MALLOCX_ARENA_BITS) - 1) << MALLOCX_ARENA_SHIFT)
+/* NB: Arena index bias decreases the maximum number of arenas by 1. */
 #define	MALLOCX_ARENA_MAX	((1 << MALLOCX_ARENA_BITS) - 2)
 #define	MALLOCX_TCACHE_MASK \
     (((1 << MALLOCX_TCACHE_BITS) - 1) << MALLOCX_TCACHE_SHIFT)
@@ -470,6 +471,7 @@ void	a0dalloc(void *ptr);
 void	*bootstrap_malloc(size_t size);
 void	*bootstrap_calloc(size_t num, size_t size);
 void	bootstrap_free(void *ptr);
+void	arena_set(unsigned ind, arena_t *arena);
 unsigned	narenas_total_get(void);
 arena_t	*arena_init(tsdn_t *tsdn, unsigned ind, extent_hooks_t *extent_hooks);
 arena_tdata_t	*arena_tdata_get_hard(tsd_t *tsd, unsigned ind);

include/jemalloc/internal/private_symbols.txt

@@ -21,6 +21,7 @@ arena_decay_time_default_get
 arena_decay_time_default_set
 arena_decay_time_get
 arena_decay_time_set
+arena_destroy
 arena_dss_prec_get
 arena_dss_prec_set
 arena_extent_alloc_large
@@ -67,6 +68,7 @@ arena_ralloc_no_move
 arena_reset
 arena_salloc
 arena_sdalloc
+arena_set
 arena_slab_regind
 arena_stats_merge
 arena_tcache_fill_small
@@ -164,6 +166,7 @@ extent_dalloc_cache
 extent_dalloc_gap
 extent_dalloc_mmap
 extent_dalloc_wrapper
+extent_dalloc_wrapper_try
 extent_decommit_wrapper
 extent_dss_boot
 extent_dss_mergeable

include/jemalloc/jemalloc_macros.h.in

@@ -44,6 +44,11 @@
  *       0);
  */
 #define	MALLCTL_ARENAS_ALL	4096
+/*
+ * Use as arena index in "stats.arenas.<i>.*" mallctl interfaces to select
+ * destroyed arenas.
+ */
+#define	MALLCTL_ARENAS_DESTROYED	4097
 
 #if defined(__cplusplus) && defined(JEMALLOC_USE_CXX_THROW)
 #  define JEMALLOC_CXX_THROW throw()