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Diffstat (limited to 'include/jemalloc/internal/emap.h')
| -rw-r--r-- | include/jemalloc/internal/emap.h | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/include/jemalloc/internal/emap.h b/include/jemalloc/internal/emap.h new file mode 100644 index 000000000..847af3278 --- /dev/null +++ b/include/jemalloc/internal/emap.h @@ -0,0 +1,357 @@ +#ifndef JEMALLOC_INTERNAL_EMAP_H +#define JEMALLOC_INTERNAL_EMAP_H + +#include "jemalloc/internal/base.h" +#include "jemalloc/internal/rtree.h" + +/* + * Note: Ends without at semicolon, so that + * EMAP_DECLARE_RTREE_CTX; + * in uses will avoid empty-statement warnings. + */ +#define EMAP_DECLARE_RTREE_CTX \ + rtree_ctx_t rtree_ctx_fallback; \ + rtree_ctx_t *rtree_ctx = tsdn_rtree_ctx(tsdn, &rtree_ctx_fallback) + +typedef struct emap_s emap_t; +struct emap_s { + rtree_t rtree; +}; + +/* Used to pass rtree lookup context down the path. */ +typedef struct emap_alloc_ctx_t emap_alloc_ctx_t; +struct emap_alloc_ctx_t { + szind_t szind; + bool slab; +}; + +typedef struct emap_full_alloc_ctx_s emap_full_alloc_ctx_t; +struct emap_full_alloc_ctx_s { + szind_t szind; + bool slab; + edata_t *edata; +}; + +bool emap_init(emap_t *emap, base_t *base, bool zeroed); + +void emap_remap(tsdn_t *tsdn, emap_t *emap, edata_t *edata, szind_t szind, + bool slab); + +void emap_update_edata_state(tsdn_t *tsdn, emap_t *emap, edata_t *edata, + extent_state_t state); + +/* + * The two acquire functions below allow accessing neighbor edatas, if it's safe + * and valid to do so (i.e. from the same arena, of the same state, etc.). This + * is necessary because the ecache locks are state based, and only protect + * edatas with the same state. Therefore the neighbor edata's state needs to be + * verified first, before chasing the edata pointer. The returned edata will be + * in an acquired state, meaning other threads will be prevented from accessing + * it, even if technically the edata can still be discovered from the rtree. + * + * This means, at any moment when holding pointers to edata, either one of the + * state based locks is held (and the edatas are all of the protected state), or + * the edatas are in an acquired state (e.g. in active or merging state). The + * acquire operation itself (changing the edata to an acquired state) is done + * under the state locks. + */ +edata_t *emap_try_acquire_edata_neighbor(tsdn_t *tsdn, emap_t *emap, + edata_t *edata, extent_pai_t pai, extent_state_t expected_state, + bool forward); +edata_t *emap_try_acquire_edata_neighbor_expand(tsdn_t *tsdn, emap_t *emap, + edata_t *edata, extent_pai_t pai, extent_state_t expected_state); +void emap_release_edata(tsdn_t *tsdn, emap_t *emap, edata_t *edata, + extent_state_t new_state); + +/* + * Associate the given edata with its beginning and end address, setting the + * szind and slab info appropriately. + * Returns true on error (i.e. resource exhaustion). + */ +bool emap_register_boundary(tsdn_t *tsdn, emap_t *emap, edata_t *edata, + szind_t szind, bool slab); + +/* + * Does the same thing, but with the interior of the range, for slab + * allocations. + * + * You might wonder why we don't just have a single emap_register function that + * does both depending on the value of 'slab'. The answer is twofold: + * - As a practical matter, in places like the extract->split->commit pathway, + * we defer the interior operation until we're sure that the commit won't fail + * (but we have to register the split boundaries there). + * - In general, we're trying to move to a world where the page-specific + * allocator doesn't know as much about how the pages it allocates will be + * used, and passing a 'slab' parameter everywhere makes that more + * complicated. + * + * Unlike the boundary version, this function can't fail; this is because slabs + * can't get big enough to touch a new page that neither of the boundaries + * touched, so no allocation is necessary to fill the interior once the boundary + * has been touched. + */ +void emap_register_interior(tsdn_t *tsdn, emap_t *emap, edata_t *edata, + szind_t szind); + +void emap_deregister_boundary(tsdn_t *tsdn, emap_t *emap, edata_t *edata); +void emap_deregister_interior(tsdn_t *tsdn, emap_t *emap, edata_t *edata); + +typedef struct emap_prepare_s emap_prepare_t; +struct emap_prepare_s { + rtree_leaf_elm_t *lead_elm_a; + rtree_leaf_elm_t *lead_elm_b; + rtree_leaf_elm_t *trail_elm_a; + rtree_leaf_elm_t *trail_elm_b; +}; + +/** + * These functions the emap metadata management for merging, splitting, and + * reusing extents. In particular, they set the boundary mappings from + * addresses to edatas. If the result is going to be used as a slab, you + * still need to call emap_register_interior on it, though. + * + * Remap simply changes the szind and slab status of an extent's boundary + * mappings. If the extent is not a slab, it doesn't bother with updating the + * end mapping (since lookups only occur in the interior of an extent for + * slabs). Since the szind and slab status only make sense for active extents, + * this should only be called while activating or deactivating an extent. + * + * Split and merge have a "prepare" and a "commit" portion. The prepare portion + * does the operations that can be done without exclusive access to the extent + * in question, while the commit variant requires exclusive access to maintain + * the emap invariants. The only function that can fail is emap_split_prepare, + * and it returns true on failure (at which point the caller shouldn't commit). + * + * In all cases, "lead" refers to the lower-addressed extent, and trail to the + * higher-addressed one. It's the caller's responsibility to set the edata + * state appropriately. + */ +bool emap_split_prepare(tsdn_t *tsdn, emap_t *emap, emap_prepare_t *prepare, + edata_t *edata, size_t size_a, edata_t *trail, size_t size_b); +void emap_split_commit(tsdn_t *tsdn, emap_t *emap, emap_prepare_t *prepare, + edata_t *lead, size_t size_a, edata_t *trail, size_t size_b); +void emap_merge_prepare(tsdn_t *tsdn, emap_t *emap, emap_prepare_t *prepare, + edata_t *lead, edata_t *trail); +void emap_merge_commit(tsdn_t *tsdn, emap_t *emap, emap_prepare_t *prepare, + edata_t *lead, edata_t *trail); + +/* Assert that the emap's view of the given edata matches the edata's view. */ +void emap_do_assert_mapped(tsdn_t *tsdn, emap_t *emap, edata_t *edata); +static inline void +emap_assert_mapped(tsdn_t *tsdn, emap_t *emap, edata_t *edata) { + if (config_debug) { + emap_do_assert_mapped(tsdn, emap, edata); + } +} + +/* Assert that the given edata isn't in the map. */ +void emap_do_assert_not_mapped(tsdn_t *tsdn, emap_t *emap, edata_t *edata); +static inline void +emap_assert_not_mapped(tsdn_t *tsdn, emap_t *emap, edata_t *edata) { + if (config_debug) { + emap_do_assert_not_mapped(tsdn, emap, edata); + } +} + +JEMALLOC_ALWAYS_INLINE bool +emap_edata_in_transition(tsdn_t *tsdn, emap_t *emap, edata_t *edata) { + assert(config_debug); + emap_assert_mapped(tsdn, emap, edata); + + EMAP_DECLARE_RTREE_CTX; + rtree_contents_t contents = rtree_read(tsdn, &emap->rtree, rtree_ctx, + (uintptr_t)edata_base_get(edata)); + + return edata_state_in_transition(contents.metadata.state); +} + +JEMALLOC_ALWAYS_INLINE bool +emap_edata_is_acquired(tsdn_t *tsdn, emap_t *emap, edata_t *edata) { + if (!config_debug) { + /* For assertions only. */ + return false; + } + + /* + * The edata is considered acquired if no other threads will attempt to + * read / write any fields from it. This includes a few cases: + * + * 1) edata not hooked into emap yet -- This implies the edata just got + * allocated or initialized. + * + * 2) in an active or transition state -- In both cases, the edata can + * be discovered from the emap, however the state tracked in the rtree + * will prevent other threads from accessing the actual edata. + */ + EMAP_DECLARE_RTREE_CTX; + rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup(tsdn, &emap->rtree, + rtree_ctx, (uintptr_t)edata_base_get(edata), /* dependent */ true, + /* init_missing */ false); + if (elm == NULL) { + return true; + } + rtree_contents_t contents = rtree_leaf_elm_read(tsdn, &emap->rtree, elm, + /* dependent */ true); + if (contents.edata == NULL || + contents.metadata.state == extent_state_active || + edata_state_in_transition(contents.metadata.state)) { + return true; + } + + return false; +} + +JEMALLOC_ALWAYS_INLINE void +extent_assert_can_coalesce(const edata_t *inner, const edata_t *outer) { + assert(edata_arena_ind_get(inner) == edata_arena_ind_get(outer)); + assert(edata_pai_get(inner) == edata_pai_get(outer)); + assert(edata_committed_get(inner) == edata_committed_get(outer)); + assert(edata_state_get(inner) == extent_state_active); + assert(edata_state_get(outer) == extent_state_merging); + assert(!edata_guarded_get(inner) && !edata_guarded_get(outer)); + assert(edata_base_get(inner) == edata_past_get(outer) || + edata_base_get(outer) == edata_past_get(inner)); +} + +JEMALLOC_ALWAYS_INLINE void +extent_assert_can_expand(const edata_t *original, const edata_t *expand) { + assert(edata_arena_ind_get(original) == edata_arena_ind_get(expand)); + assert(edata_pai_get(original) == edata_pai_get(expand)); + assert(edata_state_get(original) == extent_state_active); + assert(edata_state_get(expand) == extent_state_merging); + assert(edata_past_get(original) == edata_base_get(expand)); +} + +JEMALLOC_ALWAYS_INLINE edata_t * +emap_edata_lookup(tsdn_t *tsdn, emap_t *emap, const void *ptr) { + EMAP_DECLARE_RTREE_CTX; + + return rtree_read(tsdn, &emap->rtree, rtree_ctx, (uintptr_t)ptr).edata; +} + +/* Fills in alloc_ctx with the info in the map. */ +JEMALLOC_ALWAYS_INLINE void +emap_alloc_ctx_lookup(tsdn_t *tsdn, emap_t *emap, const void *ptr, + emap_alloc_ctx_t *alloc_ctx) { + EMAP_DECLARE_RTREE_CTX; + + rtree_metadata_t metadata = rtree_metadata_read(tsdn, &emap->rtree, + rtree_ctx, (uintptr_t)ptr); + alloc_ctx->szind = metadata.szind; + alloc_ctx->slab = metadata.slab; +} + +/* The pointer must be mapped. */ +JEMALLOC_ALWAYS_INLINE void +emap_full_alloc_ctx_lookup(tsdn_t *tsdn, emap_t *emap, const void *ptr, + emap_full_alloc_ctx_t *full_alloc_ctx) { + EMAP_DECLARE_RTREE_CTX; + + rtree_contents_t contents = rtree_read(tsdn, &emap->rtree, rtree_ctx, + (uintptr_t)ptr); + full_alloc_ctx->edata = contents.edata; + full_alloc_ctx->szind = contents.metadata.szind; + full_alloc_ctx->slab = contents.metadata.slab; +} + +/* + * The pointer is allowed to not be mapped. + * + * Returns true when the pointer is not present. + */ +JEMALLOC_ALWAYS_INLINE bool +emap_full_alloc_ctx_try_lookup(tsdn_t *tsdn, emap_t *emap, const void *ptr, + emap_full_alloc_ctx_t *full_alloc_ctx) { + EMAP_DECLARE_RTREE_CTX; + + rtree_contents_t contents; + bool err = rtree_read_independent(tsdn, &emap->rtree, rtree_ctx, + (uintptr_t)ptr, &contents); + if (err) { + return true; + } + full_alloc_ctx->edata = contents.edata; + full_alloc_ctx->szind = contents.metadata.szind; + full_alloc_ctx->slab = contents.metadata.slab; + return false; +} + +/* + * Only used on the fastpath of free. Returns true when cannot be fulfilled by + * fast path, e.g. when the metadata key is not cached. + */ +JEMALLOC_ALWAYS_INLINE bool +emap_alloc_ctx_try_lookup_fast(tsd_t *tsd, emap_t *emap, const void *ptr, + emap_alloc_ctx_t *alloc_ctx) { + /* Use the unsafe getter since this may gets called during exit. */ + rtree_ctx_t *rtree_ctx = tsd_rtree_ctxp_get_unsafe(tsd); + + rtree_metadata_t metadata; + bool err = rtree_metadata_try_read_fast(tsd_tsdn(tsd), &emap->rtree, + rtree_ctx, (uintptr_t)ptr, &metadata); + if (err) { + return true; + } + alloc_ctx->szind = metadata.szind; + alloc_ctx->slab = metadata.slab; + return false; +} + +/* + * We want to do batch lookups out of the cache bins, which use + * cache_bin_ptr_array_get to access the i'th element of the bin (since they + * invert usual ordering in deciding what to flush). This lets the emap avoid + * caring about its caller's ordering. + */ +typedef const void *(*emap_ptr_getter)(void *ctx, size_t ind); +/* + * This allows size-checking assertions, which we can only do while we're in the + * process of edata lookups. + */ +typedef void (*emap_metadata_visitor)(void *ctx, emap_full_alloc_ctx_t *alloc_ctx); + +typedef union emap_batch_lookup_result_u emap_batch_lookup_result_t; +union emap_batch_lookup_result_u { + edata_t *edata; + rtree_leaf_elm_t *rtree_leaf; +}; + +JEMALLOC_ALWAYS_INLINE void +emap_edata_lookup_batch(tsd_t *tsd, emap_t *emap, size_t nptrs, + emap_ptr_getter ptr_getter, void *ptr_getter_ctx, + emap_metadata_visitor metadata_visitor, void *metadata_visitor_ctx, + emap_batch_lookup_result_t *result) { + /* Avoids null-checking tsdn in the loop below. */ + util_assume(tsd != NULL); + rtree_ctx_t *rtree_ctx = tsd_rtree_ctxp_get(tsd); + + for (size_t i = 0; i < nptrs; i++) { + const void *ptr = ptr_getter(ptr_getter_ctx, i); + /* + * Reuse the edatas array as a temp buffer, lying a little about + * the types. + */ + result[i].rtree_leaf = rtree_leaf_elm_lookup(tsd_tsdn(tsd), + &emap->rtree, rtree_ctx, (uintptr_t)ptr, + /* dependent */ true, /* init_missing */ false); + } + + for (size_t i = 0; i < nptrs; i++) { + rtree_leaf_elm_t *elm = result[i].rtree_leaf; + rtree_contents_t contents = rtree_leaf_elm_read(tsd_tsdn(tsd), + &emap->rtree, elm, /* dependent */ true); + result[i].edata = contents.edata; + emap_full_alloc_ctx_t alloc_ctx; + /* + * Not all these fields are read in practice by the metadata + * visitor. But the compiler can easily optimize away the ones + * that aren't, so no sense in being incomplete. + */ + alloc_ctx.szind = contents.metadata.szind; + alloc_ctx.slab = contents.metadata.slab; + alloc_ctx.edata = contents.edata; + metadata_visitor(metadata_visitor_ctx, &alloc_ctx); + } +} + +#endif /* JEMALLOC_INTERNAL_EMAP_H */ |