Introduce PAI: Page allocator interface

include/jemalloc/internal/pa.h

@@ -7,6 +7,7 @@
 #include "jemalloc/internal/edata_cache.h"
 #include "jemalloc/internal/emap.h"
 #include "jemalloc/internal/lockedint.h"
+#include "jemalloc/internal/pai.h"
 
 enum pa_decay_purge_setting_e {
 	PA_DECAY_PURGE_ALWAYS,
@@ -110,6 +111,13 @@ struct pa_shard_s {
 	 */
 	atomic_zu_t nactive;
 
+	/*
+	 * An interface for page allocation from the ecache framework (i.e. a
+	 * cascade of ecache_dirty, ecache_muzzy, ecache_retained).  Right now
+	 * this is the *only* pai, but we'll soon grow another.
+	 */
+	pai_t ecache_pai;
+
 	/*
 	 * Collections of extents that were previously allocated.  These are
 	 * used when allocating extents, in an attempt to re-use address space.

include/jemalloc/internal/pai.h

@@ -0,0 +1,45 @@
+#ifndef JEMALLOC_INTERNAL_PAI_H
+#define JEMALLOC_INTERNAL_PAI_H
+
+/* An interface for page allocation. */
+
+typedef struct pai_s pai_t;
+struct pai_s {
+	/* Returns NULL on failure. */
+	edata_t *(*alloc)(tsdn_t *tsdn, pai_t *self, size_t size,
+	    size_t alignment, bool zero);
+	bool (*expand)(tsdn_t *tsdn, pai_t *self, edata_t *edata,
+	    size_t old_size, size_t new_size, bool zero);
+	bool (*shrink)(tsdn_t *tsdn, pai_t *self, edata_t *edata,
+	    size_t old_size, size_t new_size);
+	void (*dalloc)(tsdn_t *tsdn, pai_t *self, edata_t *edata);
+};
+
+/*
+ * These are just simple convenience functions to avoid having to reference the
+ * same pai_t twice on every invocation.
+ */
+
+static inline edata_t *
+pai_alloc(tsdn_t *tsdn, pai_t *self, size_t size, size_t alignment, bool zero) {
+	return self->alloc(tsdn, self, size, alignment, zero);
+}
+
+static inline bool
+pai_expand(tsdn_t *tsdn, pai_t *self, edata_t *edata, size_t old_size,
+    size_t new_size, bool zero) {
+	return self->expand(tsdn, self, edata, old_size, new_size, zero);
+}
+
+static inline bool
+pai_shrink(tsdn_t *tsdn, pai_t *self, edata_t *edata, size_t old_size,
+    size_t new_size) {
+	return self->shrink(tsdn, self, edata, old_size, new_size);
+}
+
+static inline void
+pai_dalloc(tsdn_t *tsdn, pai_t *self, edata_t *edata) {
+	self->dalloc(tsdn, self, edata);
+}
+
+#endif /* JEMALLOC_INTERNAL_PAI_H */