1 files changed, 332 insertions, 0 deletions

diff --git a/Objects/mimalloc/page-queue.c b/Objects/mimalloc/page-queue.c
new file mode 100644
index 0000000..cb54b37
--- /dev/null
+++ b/Objects/mimalloc/page-queue.c
@@ -0,0 +1,332 @@
+/*----------------------------------------------------------------------------
+Copyright (c) 2018-2020, Microsoft Research, Daan Leijen
+This is free software; you can redistribute it and/or modify it under the
+terms of the MIT license. A copy of the license can be found in the file
+"LICENSE" at the root of this distribution.
+-----------------------------------------------------------------------------*/
+
+/* -----------------------------------------------------------
+  Definition of page queues for each block size
+----------------------------------------------------------- */
+
+#ifndef MI_IN_PAGE_C
+#error "this file should be included from 'page.c'"
+#endif
+
+/* -----------------------------------------------------------
+  Minimal alignment in machine words (i.e. `sizeof(void*)`)
+----------------------------------------------------------- */
+
+#if (MI_MAX_ALIGN_SIZE > 4*MI_INTPTR_SIZE)
+  #error "define alignment for more than 4x word size for this platform"
+#elif (MI_MAX_ALIGN_SIZE > 2*MI_INTPTR_SIZE)
+  #define MI_ALIGN4W   // 4 machine words minimal alignment
+#elif (MI_MAX_ALIGN_SIZE > MI_INTPTR_SIZE)
+  #define MI_ALIGN2W   // 2 machine words minimal alignment
+#else
+  // ok, default alignment is 1 word
+#endif
+
+
+/* -----------------------------------------------------------
+  Queue query
+----------------------------------------------------------- */
+
+
+static inline bool mi_page_queue_is_huge(const mi_page_queue_t* pq) {
+  return (pq->block_size == (MI_MEDIUM_OBJ_SIZE_MAX+sizeof(uintptr_t)));
+}
+
+static inline bool mi_page_queue_is_full(const mi_page_queue_t* pq) {
+  return (pq->block_size == (MI_MEDIUM_OBJ_SIZE_MAX+(2*sizeof(uintptr_t))));
+}
+
+static inline bool mi_page_queue_is_special(const mi_page_queue_t* pq) {
+  return (pq->block_size > MI_MEDIUM_OBJ_SIZE_MAX);
+}
+
+/* -----------------------------------------------------------
+  Bins
+----------------------------------------------------------- */
+
+// Return the bin for a given field size.
+// Returns MI_BIN_HUGE if the size is too large.
+// We use `wsize` for the size in "machine word sizes",
+// i.e. byte size == `wsize*sizeof(void*)`.
+static inline uint8_t mi_bin(size_t size) {
+  size_t wsize = _mi_wsize_from_size(size);
+  uint8_t bin;
+  if (wsize <= 1) {
+    bin = 1;
+  }
+  #if defined(MI_ALIGN4W)
+  else if (wsize <= 4) {
+    bin = (uint8_t)((wsize+1)&~1); // round to double word sizes
+  }
+  #elif defined(MI_ALIGN2W)
+  else if (wsize <= 8) {
+    bin = (uint8_t)((wsize+1)&~1); // round to double word sizes
+  }
+  #else
+  else if (wsize <= 8) {
+    bin = (uint8_t)wsize;
+  }
+  #endif
+  else if (wsize > MI_MEDIUM_OBJ_WSIZE_MAX) {
+    bin = MI_BIN_HUGE;
+  }
+  else {
+    #if defined(MI_ALIGN4W)
+    if (wsize <= 16) { wsize = (wsize+3)&~3; } // round to 4x word sizes
+    #endif
+    wsize--;
+    // find the highest bit
+    uint8_t b = (uint8_t)mi_bsr(wsize);  // note: wsize != 0
+    // and use the top 3 bits to determine the bin (~12.5% worst internal fragmentation).
+    // - adjust with 3 because we use do not round the first 8 sizes
+    //   which each get an exact bin
+    bin = ((b << 2) + (uint8_t)((wsize >> (b - 2)) & 0x03)) - 3;
+    mi_assert_internal(bin < MI_BIN_HUGE);
+  }
+  mi_assert_internal(bin > 0 && bin <= MI_BIN_HUGE);
+  return bin;
+}
+
+
+
+/* -----------------------------------------------------------
+  Queue of pages with free blocks
+----------------------------------------------------------- */
+
+uint8_t _mi_bin(size_t size) {
+  return mi_bin(size);
+}
+
+size_t _mi_bin_size(uint8_t bin) {
+  return _mi_heap_empty.pages[bin].block_size;
+}
+
+// Good size for allocation
+size_t mi_good_size(size_t size) mi_attr_noexcept {
+  if (size <= MI_MEDIUM_OBJ_SIZE_MAX) {
+    return _mi_bin_size(mi_bin(size));
+  }
+  else {
+    return _mi_align_up(size,_mi_os_page_size());
+  }
+}
+
+#if (MI_DEBUG>1)
+static bool mi_page_queue_contains(mi_page_queue_t* queue, const mi_page_t* page) {
+  mi_assert_internal(page != NULL);
+  mi_page_t* list = queue->first;
+  while (list != NULL) {
+    mi_assert_internal(list->next == NULL || list->next->prev == list);
+    mi_assert_internal(list->prev == NULL || list->prev->next == list);
+    if (list == page) break;
+    list = list->next;
+  }
+  return (list == page);
+}
+
+#endif
+
+#if (MI_DEBUG>1)
+static bool mi_heap_contains_queue(const mi_heap_t* heap, const mi_page_queue_t* pq) {
+  return (pq >= &heap->pages[0] && pq <= &heap->pages[MI_BIN_FULL]);
+}
+#endif
+
+static mi_page_queue_t* mi_page_queue_of(const mi_page_t* page) {
+  uint8_t bin = (mi_page_is_in_full(page) ? MI_BIN_FULL : mi_bin(page->xblock_size));
+  mi_heap_t* heap = mi_page_heap(page);
+  mi_assert_internal(heap != NULL && bin <= MI_BIN_FULL);
+  mi_page_queue_t* pq = &heap->pages[bin];
+  mi_assert_internal(bin >= MI_BIN_HUGE || page->xblock_size == pq->block_size);
+  mi_assert_expensive(mi_page_queue_contains(pq, page));
+  return pq;
+}
+
+static mi_page_queue_t* mi_heap_page_queue_of(mi_heap_t* heap, const mi_page_t* page) {
+  uint8_t bin = (mi_page_is_in_full(page) ? MI_BIN_FULL : mi_bin(page->xblock_size));
+  mi_assert_internal(bin <= MI_BIN_FULL);
+  mi_page_queue_t* pq = &heap->pages[bin];
+  mi_assert_internal(mi_page_is_in_full(page) || page->xblock_size == pq->block_size);
+  return pq;
+}
+
+// The current small page array is for efficiency and for each
+// small size (up to 256) it points directly to the page for that
+// size without having to compute the bin. This means when the
+// current free page queue is updated for a small bin, we need to update a
+// range of entries in `_mi_page_small_free`.
+static inline void mi_heap_queue_first_update(mi_heap_t* heap, const mi_page_queue_t* pq) {
+  mi_assert_internal(mi_heap_contains_queue(heap,pq));
+  size_t size = pq->block_size;
+  if (size > MI_SMALL_SIZE_MAX) return;
+
+  mi_page_t* page = pq->first;
+  if (pq->first == NULL) page = (mi_page_t*)&_mi_page_empty;
+
+  // find index in the right direct page array
+  size_t start;
+  size_t idx = _mi_wsize_from_size(size);
+  mi_page_t** pages_free = heap->pages_free_direct;
+
+  if (pages_free[idx] == page) return;  // already set
+
+  // find start slot
+  if (idx<=1) {
+    start = 0;
+  }
+  else {
+    // find previous size; due to minimal alignment upto 3 previous bins may need to be skipped
+    uint8_t bin = mi_bin(size);
+    const mi_page_queue_t* prev = pq - 1;
+    while( bin == mi_bin(prev->block_size) && prev > &heap->pages[0]) {
+      prev--;
+    }
+    start = 1 + _mi_wsize_from_size(prev->block_size);
+    if (start > idx) start = idx;
+  }
+
+  // set size range to the right page
+  mi_assert(start <= idx);
+  for (size_t sz = start; sz <= idx; sz++) {
+    pages_free[sz] = page;
+  }
+}
+
+/*
+static bool mi_page_queue_is_empty(mi_page_queue_t* queue) {
+  return (queue->first == NULL);
+}
+*/
+
+static void mi_page_queue_remove(mi_page_queue_t* queue, mi_page_t* page) {
+  mi_assert_internal(page != NULL);
+  mi_assert_expensive(mi_page_queue_contains(queue, page));
+  mi_assert_internal(page->xblock_size == queue->block_size || (page->xblock_size > MI_MEDIUM_OBJ_SIZE_MAX && mi_page_queue_is_huge(queue))  || (mi_page_is_in_full(page) && mi_page_queue_is_full(queue)));
+  mi_heap_t* heap = mi_page_heap(page);
+
+  if (page->prev != NULL) page->prev->next = page->next;
+  if (page->next != NULL) page->next->prev = page->prev;
+  if (page == queue->last)  queue->last = page->prev;
+  if (page == queue->first) {
+    queue->first = page->next;
+    // update first
+    mi_assert_internal(mi_heap_contains_queue(heap, queue));
+    mi_heap_queue_first_update(heap,queue);
+  }
+  heap->page_count--;
+  page->next = NULL;
+  page->prev = NULL;
+  // mi_atomic_store_ptr_release(mi_atomic_cast(void*, &page->heap), NULL);
+  mi_page_set_in_full(page,false);
+}
+
+
+static void mi_page_queue_push(mi_heap_t* heap, mi_page_queue_t* queue, mi_page_t* page) {
+  mi_assert_internal(mi_page_heap(page) == heap);
+  mi_assert_internal(!mi_page_queue_contains(queue, page));
+  #if MI_HUGE_PAGE_ABANDON
+  mi_assert_internal(_mi_page_segment(page)->kind != MI_SEGMENT_HUGE);
+  #endif
+  mi_assert_internal(page->xblock_size == queue->block_size ||
+                      (page->xblock_size > MI_MEDIUM_OBJ_SIZE_MAX) ||
+                        (mi_page_is_in_full(page) && mi_page_queue_is_full(queue)));
+
+  mi_page_set_in_full(page, mi_page_queue_is_full(queue));
+  // mi_atomic_store_ptr_release(mi_atomic_cast(void*, &page->heap), heap);
+  page->next = queue->first;
+  page->prev = NULL;
+  if (queue->first != NULL) {
+    mi_assert_internal(queue->first->prev == NULL);
+    queue->first->prev = page;
+    queue->first = page;
+  }
+  else {
+    queue->first = queue->last = page;
+  }
+
+  // update direct
+  mi_heap_queue_first_update(heap, queue);
+  heap->page_count++;
+}
+
+
+static void mi_page_queue_enqueue_from(mi_page_queue_t* to, mi_page_queue_t* from, mi_page_t* page) {
+  mi_assert_internal(page != NULL);
+  mi_assert_expensive(mi_page_queue_contains(from, page));
+  mi_assert_expensive(!mi_page_queue_contains(to, page));
+
+  mi_assert_internal((page->xblock_size == to->block_size && page->xblock_size == from->block_size) ||
+                     (page->xblock_size == to->block_size && mi_page_queue_is_full(from)) ||
+                     (page->xblock_size == from->block_size && mi_page_queue_is_full(to)) ||
+                     (page->xblock_size > MI_LARGE_OBJ_SIZE_MAX && mi_page_queue_is_huge(to)) ||
+                     (page->xblock_size > MI_LARGE_OBJ_SIZE_MAX && mi_page_queue_is_full(to)));
+
+  mi_heap_t* heap = mi_page_heap(page);
+  if (page->prev != NULL) page->prev->next = page->next;
+  if (page->next != NULL) page->next->prev = page->prev;
+  if (page == from->last)  from->last = page->prev;
+  if (page == from->first) {
+    from->first = page->next;
+    // update first
+    mi_assert_internal(mi_heap_contains_queue(heap, from));
+    mi_heap_queue_first_update(heap, from);
+  }
+
+  page->prev = to->last;
+  page->next = NULL;
+  if (to->last != NULL) {
+    mi_assert_internal(heap == mi_page_heap(to->last));
+    to->last->next = page;
+    to->last = page;
+  }
+  else {
+    to->first = page;
+    to->last = page;
+    mi_heap_queue_first_update(heap, to);
+  }
+
+  mi_page_set_in_full(page, mi_page_queue_is_full(to));
+}
+
+// Only called from `mi_heap_absorb`.
+size_t _mi_page_queue_append(mi_heap_t* heap, mi_page_queue_t* pq, mi_page_queue_t* append) {
+  mi_assert_internal(mi_heap_contains_queue(heap,pq));
+  mi_assert_internal(pq->block_size == append->block_size);
+
+  if (append->first==NULL) return 0;
+
+  // set append pages to new heap and count
+  size_t count = 0;
+  for (mi_page_t* page = append->first; page != NULL; page = page->next) {
+    // inline `mi_page_set_heap` to avoid wrong assertion during absorption;
+    // in this case it is ok to be delayed freeing since both "to" and "from" heap are still alive.
+    mi_atomic_store_release(&page->xheap, (uintptr_t)heap);
+    // set the flag to delayed free (not overriding NEVER_DELAYED_FREE) which has as a
+    // side effect that it spins until any DELAYED_FREEING is finished. This ensures
+    // that after appending only the new heap will be used for delayed free operations.
+    _mi_page_use_delayed_free(page, MI_USE_DELAYED_FREE, false);
+    count++;
+  }
+
+  if (pq->last==NULL) {
+    // take over afresh
+    mi_assert_internal(pq->first==NULL);
+    pq->first = append->first;
+    pq->last = append->last;
+    mi_heap_queue_first_update(heap, pq);
+  }
+  else {
+    // append to end
+    mi_assert_internal(pq->last!=NULL);
+    mi_assert_internal(append->first!=NULL);
+    pq->last->next = append->first;
+    append->first->prev = pq->last;
+    pq->last = append->last;
+  }
+  return count;
+}