1 files changed, 271 insertions, 0 deletions
diff --git a/deps/jemalloc/src/extent_dss.c b/deps/jemalloc/src/extent_dss.c
new file mode 100644
index 0000000..8581789
--- /dev/null
+++ b/deps/jemalloc/src/extent_dss.c
@@ -0,0 +1,271 @@
+#define JEMALLOC_EXTENT_DSS_C_
+#include "jemalloc/internal/jemalloc_preamble.h"
+#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+#include "jemalloc/internal/assert.h"
+#include "jemalloc/internal/extent_dss.h"
+#include "jemalloc/internal/spin.h"
+
+/******************************************************************************/
+/* Data. */
+
+const char	*opt_dss = DSS_DEFAULT;
+
+const char	*dss_prec_names[] = {
+	"disabled",
+	"primary",
+	"secondary",
+	"N/A"
+};
+
+/*
+ * Current dss precedence default, used when creating new arenas.  NB: This is
+ * stored as unsigned rather than dss_prec_t because in principle there's no
+ * guarantee that sizeof(dss_prec_t) is the same as sizeof(unsigned), and we use
+ * atomic operations to synchronize the setting.
+ */
+static atomic_u_t	dss_prec_default = ATOMIC_INIT(
+    (unsigned)DSS_PREC_DEFAULT);
+
+/* Base address of the DSS. */
+static void		*dss_base;
+/* Atomic boolean indicating whether a thread is currently extending DSS. */
+static atomic_b_t	dss_extending;
+/* Atomic boolean indicating whether the DSS is exhausted. */
+static atomic_b_t	dss_exhausted;
+/* Atomic current upper limit on DSS addresses. */
+static atomic_p_t	dss_max;
+
+/******************************************************************************/
+
+static void *
+extent_dss_sbrk(intptr_t increment) {
+#ifdef JEMALLOC_DSS
+	return sbrk(increment);
+#else
+	not_implemented();
+	return NULL;
+#endif
+}
+
+dss_prec_t
+extent_dss_prec_get(void) {
+	dss_prec_t ret;
+
+	if (!have_dss) {
+		return dss_prec_disabled;
+	}
+	ret = (dss_prec_t)atomic_load_u(&dss_prec_default, ATOMIC_ACQUIRE);
+	return ret;
+}
+
+bool
+extent_dss_prec_set(dss_prec_t dss_prec) {
+	if (!have_dss) {
+		return (dss_prec != dss_prec_disabled);
+	}
+	atomic_store_u(&dss_prec_default, (unsigned)dss_prec, ATOMIC_RELEASE);
+	return false;
+}
+
+static void
+extent_dss_extending_start(void) {
+	spin_t spinner = SPIN_INITIALIZER;
+	while (true) {
+		bool expected = false;
+		if (atomic_compare_exchange_weak_b(&dss_extending, &expected,
+		    true, ATOMIC_ACQ_REL, ATOMIC_RELAXED)) {
+			break;
+		}
+		spin_adaptive(&spinner);
+	}
+}
+
+static void
+extent_dss_extending_finish(void) {
+	assert(atomic_load_b(&dss_extending, ATOMIC_RELAXED));
+
+	atomic_store_b(&dss_extending, false, ATOMIC_RELEASE);
+}
+
+static void *
+extent_dss_max_update(void *new_addr) {
+	/*
+	 * Get the current end of the DSS as max_cur and assure that dss_max is
+	 * up to date.
+	 */
+	void *max_cur = extent_dss_sbrk(0);
+	if (max_cur == (void *)-1) {
+		return NULL;
+	}
+	atomic_store_p(&dss_max, max_cur, ATOMIC_RELEASE);
+	/* Fixed new_addr can only be supported if it is at the edge of DSS. */
+	if (new_addr != NULL && max_cur != new_addr) {
+		return NULL;
+	}
+	return max_cur;
+}
+
+void *
+extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
+    size_t alignment, bool *zero, bool *commit) {
+	extent_t *gap;
+
+	cassert(have_dss);
+	assert(size > 0);
+	assert(alignment == ALIGNMENT_CEILING(alignment, PAGE));
+
+	/*
+	 * sbrk() uses a signed increment argument, so take care not to
+	 * interpret a large allocation request as a negative increment.
+	 */
+	if ((intptr_t)size < 0) {
+		return NULL;
+	}
+
+	gap = extent_alloc(tsdn, arena);
+	if (gap == NULL) {
+		return NULL;
+	}
+
+	extent_dss_extending_start();
+	if (!atomic_load_b(&dss_exhausted, ATOMIC_ACQUIRE)) {
+		/*
+		 * The loop is necessary to recover from races with other
+		 * threads that are using the DSS for something other than
+		 * malloc.
+		 */
+		while (true) {
+			void *max_cur = extent_dss_max_update(new_addr);
+			if (max_cur == NULL) {
+				goto label_oom;
+			}
+
+			/*
+			 * Compute how much page-aligned gap space (if any) is
+			 * necessary to satisfy alignment.  This space can be
+			 * recycled for later use.
+			 */
+			void *gap_addr_page = (void *)(PAGE_CEILING(
+			    (uintptr_t)max_cur));
+			void *ret = (void *)ALIGNMENT_CEILING(
+			    (uintptr_t)gap_addr_page, alignment);
+			size_t gap_size_page = (uintptr_t)ret -
+			    (uintptr_t)gap_addr_page;
+			if (gap_size_page != 0) {
+				extent_init(gap, arena, gap_addr_page,
+				    gap_size_page, false, SC_NSIZES,
+				    arena_extent_sn_next(arena),
+				    extent_state_active, false, true, true,
+				    EXTENT_NOT_HEAD);
+			}
+			/*
+			 * Compute the address just past the end of the desired
+			 * allocation space.
+			 */
+			void *dss_next = (void *)((uintptr_t)ret + size);
+			if ((uintptr_t)ret < (uintptr_t)max_cur ||
+			    (uintptr_t)dss_next < (uintptr_t)max_cur) {
+				goto label_oom; /* Wrap-around. */
+			}
+			/* Compute the increment, including subpage bytes. */
+			void *gap_addr_subpage = max_cur;
+			size_t gap_size_subpage = (uintptr_t)ret -
+			    (uintptr_t)gap_addr_subpage;
+			intptr_t incr = gap_size_subpage + size;
+
+			assert((uintptr_t)max_cur + incr == (uintptr_t)ret +
+			    size);
+
+			/* Try to allocate. */
+			void *dss_prev = extent_dss_sbrk(incr);
+			if (dss_prev == max_cur) {
+				/* Success. */
+				atomic_store_p(&dss_max, dss_next,
+				    ATOMIC_RELEASE);
+				extent_dss_extending_finish();
+
+				if (gap_size_page != 0) {
+					extent_dalloc_gap(tsdn, arena, gap);
+				} else {
+					extent_dalloc(tsdn, arena, gap);
+				}
+				if (!*commit) {
+					*commit = pages_decommit(ret, size);
+				}
+				if (*zero && *commit) {
+					extent_hooks_t *extent_hooks =
+					    EXTENT_HOOKS_INITIALIZER;
+					extent_t extent;
+
+					extent_init(&extent, arena, ret, size,
+					    size, false, SC_NSIZES,
+					    extent_state_active, false, true,
+					    true, EXTENT_NOT_HEAD);
+					if (extent_purge_forced_wrapper(tsdn,
+					    arena, &extent_hooks, &extent, 0,
+					    size)) {
+						memset(ret, 0, size);
+					}
+				}
+				return ret;
+			}
+			/*
+			 * Failure, whether due to OOM or a race with a raw
+			 * sbrk() call from outside the allocator.
+			 */
+			if (dss_prev == (void *)-1) {
+				/* OOM. */
+				atomic_store_b(&dss_exhausted, true,
+				    ATOMIC_RELEASE);
+				goto label_oom;
+			}
+		}
+	}
+label_oom:
+	extent_dss_extending_finish();
+	extent_dalloc(tsdn, arena, gap);
+	return NULL;
+}
+
+static bool
+extent_in_dss_helper(void *addr, void *max) {
+	return ((uintptr_t)addr >= (uintptr_t)dss_base && (uintptr_t)addr <
+	    (uintptr_t)max);
+}
+
+bool
+extent_in_dss(void *addr) {
+	cassert(have_dss);
+
+	return extent_in_dss_helper(addr, atomic_load_p(&dss_max,
+	    ATOMIC_ACQUIRE));
+}
+
+bool
+extent_dss_mergeable(void *addr_a, void *addr_b) {
+	void *max;
+
+	cassert(have_dss);
+
+	if ((uintptr_t)addr_a < (uintptr_t)dss_base && (uintptr_t)addr_b <
+	    (uintptr_t)dss_base) {
+		return true;
+	}
+
+	max = atomic_load_p(&dss_max, ATOMIC_ACQUIRE);
+	return (extent_in_dss_helper(addr_a, max) ==
+	    extent_in_dss_helper(addr_b, max));
+}
+
+void
+extent_dss_boot(void) {
+	cassert(have_dss);
+
+	dss_base = extent_dss_sbrk(0);
+	atomic_store_b(&dss_extending, false, ATOMIC_RELAXED);
+	atomic_store_b(&dss_exhausted, dss_base == (void *)-1, ATOMIC_RELAXED);
+	atomic_store_p(&dss_max, dss_base, ATOMIC_RELAXED);
+}
+
+/******************************************************************************/