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Diffstat (limited to 'absl/base/internal/malloc_extension.h')
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diff --git a/absl/base/internal/malloc_extension.h b/absl/base/internal/malloc_extension.h new file mode 100644 index 0000000..dee4116 --- /dev/null +++ b/absl/base/internal/malloc_extension.h @@ -0,0 +1,424 @@ +// +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// + +// Extra extensions exported by some malloc implementations. These +// extensions are accessed through a virtual base class so an +// application can link against a malloc that does not implement these +// extensions, and it will get default versions that do nothing. +// +// NOTE FOR C USERS: If you wish to use this functionality from within +// a C program, see malloc_extension_c.h. + +#ifndef ABSL_BASE_INTERNAL_MALLOC_EXTENSION_H_ +#define ABSL_BASE_INTERNAL_MALLOC_EXTENSION_H_ + +#include <atomic> +#include <map> +#include <memory> +#include <vector> + +#include <stddef.h> +#include <stdint.h> +#include <string> +#include "absl/base/macros.h" +#include "absl/base/port.h" +namespace absl { +namespace base_internal { + +class MallocExtensionWriter; + +// Interface to a pluggable system allocator. +class SysAllocator { + public: + SysAllocator() { + } + virtual ~SysAllocator(); + + // Allocates "size"-byte of memory from system aligned with "alignment". + // Returns null if failed. Otherwise, the returned pointer p up to and + // including (p + actual_size -1) have been allocated. + virtual void* Alloc(size_t size, size_t *actual_size, size_t alignment) = 0; + + // Get a human-readable description of the current state of the + // allocator. The state is stored as a null-terminated std::string in + // a prefix of buffer. + virtual void GetStats(char* buffer, int length); +}; + +// The default implementations of the following routines do nothing. +// All implementations should be thread-safe; the current ones +// (DebugMallocImplementation and TCMallocImplementation) are. +class MallocExtension { + public: + virtual ~MallocExtension(); + + // Verifies that all blocks are valid. Returns true if all are; dumps + // core otherwise. A no-op except in debug mode. Even in debug mode, + // they may not do any checking except with certain malloc + // implementations. Thread-safe. + virtual bool VerifyAllMemory(); + + // Verifies that p was returned by new, has not been deleted, and is + // valid. Returns true if p is good; dumps core otherwise. A no-op + // except in debug mode. Even in debug mode, may not do any checking + // except with certain malloc implementations. Thread-safe. + virtual bool VerifyNewMemory(const void* p); + + // Verifies that p was returned by new[], has not been deleted, and is + // valid. Returns true if p is good; dumps core otherwise. A no-op + // except in debug mode. Even in debug mode, may not do any checking + // except with certain malloc implementations. Thread-safe. + virtual bool VerifyArrayNewMemory(const void* p); + + // Verifies that p was returned by malloc, has not been freed, and is + // valid. Returns true if p is good; dumps core otherwise. A no-op + // except in debug mode. Even in debug mode, may not do any checking + // except with certain malloc implementations. Thread-safe. + virtual bool VerifyMallocMemory(const void* p); + + // If statistics collection is enabled, sets *blocks to be the number of + // currently allocated blocks, sets *total to be the total size allocated + // over all blocks, sets histogram[n] to be the number of blocks with + // size between 2^n-1 and 2^(n+1), and returns true. Returns false, and + // does not change *blocks, *total, or *histogram, if statistics + // collection is disabled. + // + // Note that these statistics reflect memory allocated by new, new[], + // malloc(), and realloc(), but not mmap(). They may be larger (if not + // all pages have been written to) or smaller (if pages have been + // allocated by mmap()) than the total RSS size. They will always be + // smaller than the total virtual memory size. + static constexpr int kMallocHistogramSize = 64; + virtual bool MallocMemoryStats(int* blocks, size_t* total, + int histogram[kMallocHistogramSize]); + + // Get a human readable description of the current state of the malloc + // data structures. The state is stored as a null-terminated std::string + // in a prefix of "buffer[0,buffer_length-1]". + // REQUIRES: buffer_length > 0. + virtual void GetStats(char* buffer, int buffer_length); + + // Outputs to "writer" a sample of live objects and the stack traces + // that allocated these objects. The output can be passed to pprof. + virtual void GetHeapSample(MallocExtensionWriter* writer); + + // Outputs to "writer" the stack traces that caused growth in the + // address space size. The output can be passed to "pprof". + virtual void GetHeapGrowthStacks(MallocExtensionWriter* writer); + + // Outputs to "writer" a fragmentation profile. The output can be + // passed to "pprof". In particular, the result is a list of + // <n,total,stacktrace> tuples that says that "total" bytes in "n" + // objects are currently unusable because of fragmentation caused by + // an allocation with the specified "stacktrace". + virtual void GetFragmentationProfile(MallocExtensionWriter* writer); + + // ------------------------------------------------------------------- + // Control operations for getting and setting malloc implementation + // specific parameters. Some currently useful properties: + // + // generic + // ------- + // "generic.current_allocated_bytes" + // Number of bytes currently allocated by application + // This property is not writable. + // + // "generic.heap_size" + // Number of bytes in the heap == + // current_allocated_bytes + + // fragmentation + + // freed memory regions + // This property is not writable. + // + // tcmalloc + // -------- + // "tcmalloc.max_total_thread_cache_bytes" + // Upper limit on total number of bytes stored across all + // per-thread caches. Default: 16MB. + // + // "tcmalloc.current_total_thread_cache_bytes" + // Number of bytes used across all thread caches. + // This property is not writable. + // + // "tcmalloc.pageheap_free_bytes" + // Number of bytes in free, mapped pages in page heap. These + // bytes can be used to fulfill allocation requests. They + // always count towards virtual memory usage, and unless the + // underlying memory is swapped out by the OS, they also count + // towards physical memory usage. This property is not writable. + // + // "tcmalloc.pageheap_unmapped_bytes" + // Number of bytes in free, unmapped pages in page heap. + // These are bytes that have been released back to the OS, + // possibly by one of the MallocExtension "Release" calls. + // They can be used to fulfill allocation requests, but + // typically incur a page fault. They always count towards + // virtual memory usage, and depending on the OS, typically + // do not count towards physical memory usage. This property + // is not writable. + // + // "tcmalloc.per_cpu_caches_active" + // Whether tcmalloc is using per-CPU caches (1 or 0 respectively). + // This property is not writable. + // ------------------------------------------------------------------- + + // Get the named "property"'s value. Returns true if the property + // is known. Returns false if the property is not a valid property + // name for the current malloc implementation. + // REQUIRES: property != null; value != null + virtual bool GetNumericProperty(const char* property, size_t* value); + + // Set the named "property"'s value. Returns true if the property + // is known and writable. Returns false if the property is not a + // valid property name for the current malloc implementation, or + // is not writable. + // REQUIRES: property != null + virtual bool SetNumericProperty(const char* property, size_t value); + + // Mark the current thread as "idle". This routine may optionally + // be called by threads as a hint to the malloc implementation that + // any thread-specific resources should be released. Note: this may + // be an expensive routine, so it should not be called too often. + // + // Also, if the code that calls this routine will go to sleep for + // a while, it should take care to not allocate anything between + // the call to this routine and the beginning of the sleep. + // + // Most malloc implementations ignore this routine. + virtual void MarkThreadIdle(); + + // Mark the current thread as "busy". This routine should be + // called after MarkThreadIdle() if the thread will now do more + // work. If this method is not called, performance may suffer. + // + // Most malloc implementations ignore this routine. + virtual void MarkThreadBusy(); + + // Attempt to free any resources associated with cpu <cpu> (in the sense + // of only being usable from that CPU.) Returns the number of bytes + // previously assigned to "cpu" that were freed. Safe to call from + // any processor, not just <cpu>. + // + // Most malloc implementations ignore this routine (known exceptions: + // tcmalloc with --tcmalloc_per_cpu_caches=true.) + virtual size_t ReleaseCPUMemory(int cpu); + + // Gets the system allocator used by the malloc extension instance. Returns + // null for malloc implementations that do not support pluggable system + // allocators. + virtual SysAllocator* GetSystemAllocator(); + + // Sets the system allocator to the specified. + // + // Users could register their own system allocators for malloc implementation + // that supports pluggable system allocators, such as TCMalloc, by doing: + // alloc = new MyOwnSysAllocator(); + // MallocExtension::instance()->SetSystemAllocator(alloc); + // It's up to users whether to fall back (recommended) to the default + // system allocator (use GetSystemAllocator() above) or not. The caller is + // responsible to any necessary locking. + // See tcmalloc/system-alloc.h for the interface and + // tcmalloc/memfs_malloc.cc for the examples. + // + // It's a no-op for malloc implementations that do not support pluggable + // system allocators. + virtual void SetSystemAllocator(SysAllocator *a); + + // Try to release num_bytes of free memory back to the operating + // system for reuse. Use this extension with caution -- to get this + // memory back may require faulting pages back in by the OS, and + // that may be slow. (Currently only implemented in tcmalloc.) + virtual void ReleaseToSystem(size_t num_bytes); + + // Same as ReleaseToSystem() but release as much memory as possible. + virtual void ReleaseFreeMemory(); + + // Sets the rate at which we release unused memory to the system. + // Zero means we never release memory back to the system. Increase + // this flag to return memory faster; decrease it to return memory + // slower. Reasonable rates are in the range [0,10]. (Currently + // only implemented in tcmalloc). + virtual void SetMemoryReleaseRate(double rate); + + // Gets the release rate. Returns a value < 0 if unknown. + virtual double GetMemoryReleaseRate(); + + // Returns the estimated number of bytes that will be allocated for + // a request of "size" bytes. This is an estimate: an allocation of + // SIZE bytes may reserve more bytes, but will never reserve less. + // (Currently only implemented in tcmalloc, other implementations + // always return SIZE.) + // This is equivalent to malloc_good_size() in OS X. + virtual size_t GetEstimatedAllocatedSize(size_t size); + + // Returns the actual number N of bytes reserved by tcmalloc for the + // pointer p. This number may be equal to or greater than the + // number of bytes requested when p was allocated. + // + // This routine is just useful for statistics collection. The + // client must *not* read or write from the extra bytes that are + // indicated by this call. + // + // Example, suppose the client gets memory by calling + // p = malloc(10) + // and GetAllocatedSize(p) returns 16. The client must only use the + // first 10 bytes p[0..9], and not attempt to read or write p[10..15]. + // + // p must have been allocated by this malloc implementation, must + // not be an interior pointer -- that is, must be exactly the + // pointer returned to by malloc() et al., not some offset from that + // -- and should not have been freed yet. p may be null. + // (Currently only implemented in tcmalloc; other implementations + // will return 0.) + virtual size_t GetAllocatedSize(const void* p); + + // Returns kOwned if this malloc implementation allocated the memory + // pointed to by p, or kNotOwned if some other malloc implementation + // allocated it or p is null. May also return kUnknownOwnership if + // the malloc implementation does not keep track of ownership. + // REQUIRES: p must be a value returned from a previous call to + // malloc(), calloc(), realloc(), memalign(), posix_memalign(), + // valloc(), pvalloc(), new, or new[], and must refer to memory that + // is currently allocated (so, for instance, you should not pass in + // a pointer after having called free() on it). + enum Ownership { + // NOTE: Enum values MUST be kept in sync with the version in + // malloc_extension_c.h + kUnknownOwnership = 0, + kOwned, + kNotOwned + }; + virtual Ownership GetOwnership(const void* p); + + // The current malloc implementation. Always non-null. + static MallocExtension* instance() { + InitModuleOnce(); + return current_instance_.load(std::memory_order_acquire); + } + + // Change the malloc implementation. Typically called by the + // malloc implementation during initialization. + static void Register(MallocExtension* implementation); + + // Type used by GetProperties. See comment on GetProperties. + struct Property { + size_t value; + // Stores breakdown of the property value bucketed by object size. + struct Bucket { + size_t min_object_size; + size_t max_object_size; + size_t size; + }; + // Empty unless detailed info was asked for and this type has buckets + std::vector<Bucket> buckets; + }; + + // Type used by GetProperties. See comment on GetProperties. + enum StatLevel { kSummary, kDetailed }; + + // Stores in *result detailed statistics about the malloc + // implementation. *result will be a map keyed by the name of + // the statistic. Each statistic has at least a "value" field. + // + // Some statistics may also contain an array of buckets if + // level==kDetailed and the "value" can be subdivided + // into different buckets for different object sizes. If + // such detailed statistics are not available, Property::buckets + // will be empty. Otherwise Property::buckets will contain + // potentially many entries. For each bucket b, b.value + // will count the value contributed by objects in the range + // [b.min_object_size, b.max_object_size]. + // + // Common across malloc implementations: + // generic.bytes_in_use_by_app -- Bytes currently in use by application + // generic.physical_memory_used -- Overall (including malloc internals) + // generic.virtual_memory_used -- Overall (including malloc internals) + // + // Tcmalloc specific properties + // tcmalloc.cpu_free -- Bytes in per-cpu free-lists + // tcmalloc.thread_cache_free -- Bytes in per-thread free-lists + // tcmalloc.transfer_cache -- Bytes in cross-thread transfer caches + // tcmalloc.central_cache_free -- Bytes in central cache + // tcmalloc.page_heap_free -- Bytes in page heap + // tcmalloc.page_heap_unmapped -- Bytes in page heap (no backing phys. mem) + // tcmalloc.metadata_bytes -- Used by internal data structures + // tcmalloc.thread_cache_count -- Number of thread caches in use + // + // Debug allocator + // debug.free_queue -- Recently freed objects + virtual void GetProperties(StatLevel level, + std::map<std::string, Property>* result); + private: + static MallocExtension* InitModule(); + + static void InitModuleOnce() { + // Pointer stored here so heap leak checker will consider the default + // instance reachable, even if current_instance_ is later overridden by + // MallocExtension::Register(). + ABSL_ATTRIBUTE_UNUSED static MallocExtension* default_instance = + InitModule(); + } + + static std::atomic<MallocExtension*> current_instance_; +}; + +// Base class than can handle output generated by GetHeapSample() and +// GetHeapGrowthStacks(). Use the available subclass or roll your +// own. Useful if you want explicit control over the type of output +// buffer used (e.g. IOBuffer, Cord, etc.) +class MallocExtensionWriter { + public: + virtual ~MallocExtensionWriter() {} + virtual void Write(const char* buf, int len) = 0; + protected: + MallocExtensionWriter() {} + MallocExtensionWriter(const MallocExtensionWriter&) = delete; + MallocExtensionWriter& operator=(const MallocExtensionWriter&) = delete; +}; + +// A subclass that writes to the std::string "out". NOTE: The generated +// data is *appended* to "*out". I.e., the old contents of "*out" are +// preserved. +class StringMallocExtensionWriter : public MallocExtensionWriter { + public: + explicit StringMallocExtensionWriter(std::string* out) : out_(out) {} + virtual void Write(const char* buf, int len) { + out_->append(buf, len); + } + + private: + std::string* const out_; + StringMallocExtensionWriter(const StringMallocExtensionWriter&) = delete; + StringMallocExtensionWriter& operator=(const StringMallocExtensionWriter&) = + delete; +}; + +} // namespace base_internal +} // namespace absl + +// The nallocx function allocates no memory, but it performs the same size +// computation as the malloc function, and returns the real size of the +// allocation that would result from the equivalent malloc function call. +// Default weak implementation returns size unchanged, but tcmalloc overrides it +// and returns rounded up size. See the following link for details: +// http://www.unix.com/man-page/freebsd/3/nallocx/ +extern "C" size_t nallocx(size_t size, int flags); + +#ifndef MALLOCX_LG_ALIGN +#define MALLOCX_LG_ALIGN(la) (la) +#endif + +#endif // ABSL_BASE_INTERNAL_MALLOC_EXTENSION_H_ |