Extent refactor: Introduce ecache module.

This will eventually completely wrap the eset, and handle concurrency,
allocation, and deallocation.  For now, we only pull out the mutex from the
eset.

src/ecache.c

@@ -0,0 +1,54 @@
+#include "jemalloc/internal/jemalloc_preamble.h"
+#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+bool
+ecache_init(tsdn_t *tsdn, ecache_t *ecache, extent_state_t state,
+    bool delay_coalesce) {
+	if (malloc_mutex_init(&ecache->mtx, "extents", WITNESS_RANK_EXTENTS,
+	    malloc_mutex_rank_exclusive)) {
+		return true;
+	}
+	eset_init(&ecache->eset, state, delay_coalesce);
+	return false;
+}
+
+void
+ecache_prefork(tsdn_t *tsdn, ecache_t *ecache) {
+	malloc_mutex_prefork(tsdn, &ecache->mtx);
+}
+
+void
+ecache_postfork_parent(tsdn_t *tsdn, ecache_t *ecache) {
+	malloc_mutex_postfork_parent(tsdn, &ecache->mtx);
+}
+
+void
+ecache_postfork_child(tsdn_t *tsdn, ecache_t *ecache) {
+	malloc_mutex_postfork_child(tsdn, &ecache->mtx);
+}
+
+bool
+ecache_grow_init(tsdn_t *tsdn, ecache_grow_t *ecache_grow) {
+	ecache_grow->next = sz_psz2ind(HUGEPAGE);
+	ecache_grow->limit = sz_psz2ind(SC_LARGE_MAXCLASS);
+	if (malloc_mutex_init(&ecache_grow->mtx, "extent_grow",
+	    WITNESS_RANK_EXTENT_GROW, malloc_mutex_rank_exclusive)) {
+		return true;
+	}
+	return false;
+}
+
+void
+ecache_grow_prefork(tsdn_t *tsdn, ecache_grow_t *ecache_grow) {
+	malloc_mutex_prefork(tsdn, &ecache_grow->mtx);
+}
+
+void
+ecache_grow_postfork_parent(tsdn_t *tsdn, ecache_grow_t *ecache_grow) {
+	malloc_mutex_postfork_parent(tsdn, &ecache_grow->mtx);
+}
+
+void
+ecache_grow_postfork_child(tsdn_t *tsdn, ecache_grow_t *ecache_grow) {
+	malloc_mutex_postfork_child(tsdn, &ecache_grow->mtx);
+}