1 files changed, 216 insertions, 0 deletions
diff --git a/contrib/llvm-project/lldb/include/lldb/Core/DataFileCache.h b/contrib/llvm-project/lldb/include/lldb/Core/DataFileCache.h
new file mode 100644
index 000000000000..3016c531f674
--- /dev/null
+++ b/contrib/llvm-project/lldb/include/lldb/Core/DataFileCache.h
@@ -0,0 +1,216 @@
+//===-- DataFileCache.h -----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_CORE_DATAFILECACHE_H
+#define LLDB_CORE_DATAFILECACHE_H
+
+#include "lldb/Utility/FileSpec.h"
+#include "lldb/Utility/Status.h"
+#include "lldb/Utility/UUID.h"
+#include "lldb/lldb-forward.h"
+#include "llvm/Support/Caching.h"
+#include <mutex>
+
+namespace lldb_private {
+
+/// This class enables data to be cached into a directory using the llvm
+/// caching code. Data can be stored and accessed using a unique string key.
+/// The data will be stored in the directory that is specified in the
+/// DataFileCache constructor. The data will be stored in files that start with
+/// "llvmcache-<key>" where <key> is the key name specified when getting to
+/// setting cached data.
+///
+/// Sample code for how to use the cache:
+///
+///   DataFileCache cache("/tmp/lldb-test-cache");
+///   StringRef key("Key1");
+///   auto mem_buffer_up = cache.GetCachedData(key);
+///   if (mem_buffer_up) {
+///     printf("cached data:\n%s", mem_buffer_up->getBufferStart());
+///   } else {
+///     std::vector<uint8_t> data = { 'h', 'e', 'l', 'l', 'o', '\n' };
+///     cache.SetCachedData(key, data);
+///   }
+
+class DataFileCache {
+public:
+  /// Create a data file cache in the directory path that is specified.
+  ///
+  /// Data will be cached in files created in this directory when clients call
+  /// DataFileCache::SetCacheData.
+  DataFileCache(llvm::StringRef path);
+
+  /// Get cached data from the cache directory for the specified key.
+  ///
+  /// Keys must be unique for any given data. This function attempts to see if
+  /// the data is available for the specified key and will return a valid memory
+  /// buffer is data is available.
+  ///
+  /// \param key
+  ///   The unique string key that identifies data being cached.
+  ///
+  /// \return
+  ///   A valid unique pointer to a memory buffer if the data is available, or
+  ///   a unique pointer that contains NULL if the data is not available.
+  std::unique_ptr<llvm::MemoryBuffer> GetCachedData(llvm::StringRef key);
+
+  /// Set cached data for the specified key.
+  ///
+  /// Setting the cached data will save a file in the cache directory to contain
+  /// the specified data.
+  ///
+  /// \param key
+  ///   The unique string key that identifies data being cached.
+  ///
+  /// \return
+  ///   True if the data was successfully cached, false otherwise.
+  bool SetCachedData(llvm::StringRef key, llvm::ArrayRef<uint8_t> data);
+
+  /// Remove the cache file associated with the key.
+  Status RemoveCacheFile(llvm::StringRef key);
+
+private:
+  /// Return the cache file that is associated with the key.
+  FileSpec GetCacheFilePath(llvm::StringRef key);
+
+  llvm::FileCache m_cache_callback;
+  FileSpec m_cache_dir;
+  std::mutex m_mutex;
+  std::unique_ptr<llvm::MemoryBuffer> m_mem_buff_up;
+  bool m_take_ownership = false;
+};
+
+/// A signature for a given file on disk.
+///
+/// Any files that are cached in the LLDB index cached need some data that
+/// uniquely identifies a file on disk and this information should be written
+/// into each cache file so we can validate if the cache file still matches
+/// the file we are trying to load cached data for. Objects can fill out this
+/// signature and then encode and decode them to validate the signatures
+/// match. If they do not match, the cache file on disk should be removed as
+/// it is out of date.
+struct CacheSignature {
+  /// UUID of object file or module.
+  llvm::Optional<UUID> m_uuid = llvm::None;
+  /// Modification time of file on disk.
+  llvm::Optional<std::time_t> m_mod_time = llvm::None;
+  /// If this describes a .o file with a BSD archive, the BSD archive's
+  /// modification time will be in m_mod_time, and the .o file's modification
+  /// time will be in this m_obj_mod_time.
+  llvm::Optional<std::time_t> m_obj_mod_time = llvm::None;
+
+  CacheSignature() = default;
+
+  /// Create a signature from a module.
+  CacheSignature(lldb_private::Module *module);
+
+  /// Create a signature from an object file.
+  CacheSignature(lldb_private::ObjectFile *objfile);
+
+  void Clear() {
+    m_uuid = llvm::None;
+    m_mod_time = llvm::None;
+    m_obj_mod_time = llvm::None;
+  }
+
+  /// Return true if any of the signature member variables have valid values.
+  bool IsValid() const {
+    return m_uuid.hasValue() || m_mod_time.hasValue() ||
+           m_obj_mod_time.hasValue();
+  }
+
+  /// Check if two signatures are the same.
+  bool operator!=(const CacheSignature &rhs) {
+    if (m_uuid != rhs.m_uuid)
+      return true;
+    if (m_mod_time != rhs.m_mod_time)
+      return true;
+    if (m_obj_mod_time != rhs.m_obj_mod_time)
+      return true;
+    return false;
+  }
+  /// Encode this object into a data encoder object.
+  ///
+  /// This allows this object to be serialized to disk. The CacheSignature
+  /// object must have at least one member variable that has a value in order to
+  /// be serialized so that we can match this data to when the cached file is
+  /// loaded at a later time.
+  ///
+  /// \param encoder
+  ///   A data encoder object that serialized bytes will be encoded into.
+  ///
+  /// \return
+  ///   True if a signature was encoded, and false if there were no member
+  ///   variables that had value. False indicates this data should not be
+  ///   cached to disk because we were unable to encode a valid signature.
+  bool Encode(DataEncoder &encoder);
+
+  /// Decode a serialized version of this object from data.
+  ///
+  /// \param data
+  ///   The decoder object that references the serialized data.
+  ///
+  /// \param offset_ptr
+  ///   A pointer that contains the offset from which the data will be decoded
+  ///   from that gets updated as data gets decoded.
+  ///
+  /// \return
+  ///   True if the signature was successfully decoded, false otherwise.
+  bool Decode(const DataExtractor &data, lldb::offset_t *offset_ptr);
+};
+
+/// Many cache files require string tables to store data efficiently. This
+/// class helps create string tables.
+class ConstStringTable {
+public:
+  ConstStringTable() = default;
+  /// Add a string into the string table.
+  ///
+  /// Add a string to the string table will only add the same string one time
+  /// and will return the offset in the string table buffer to that string.
+  /// String tables are easy to build with ConstString objects since most LLDB
+  /// classes for symbol or debug info use them already and they provide
+  /// permanent storage for the string.
+  ///
+  /// \param s
+  ///   The string to insert into the string table.
+  ///
+  /// \return
+  ///   The byte offset from the start of the string table for the inserted
+  ///   string. Duplicate strings that get inserted will return the same
+  ///   byte offset.
+  uint32_t Add(ConstString s);
+
+  bool Encode(DataEncoder &encoder);
+
+private:
+  std::vector<ConstString> m_strings;
+  std::map<ConstString, uint32_t> m_string_to_offset;
+  /// Skip one byte to start the string table off with an empty string.
+  uint32_t m_next_offset = 1;
+};
+
+/// Many cache files require string tables to store data efficiently. This
+/// class helps give out strings from a string table that was read from a
+/// cache file.
+class StringTableReader {
+public:
+  StringTableReader() = default;
+
+  llvm::StringRef Get(uint32_t offset) const;
+
+  bool Decode(const DataExtractor &data, lldb::offset_t *offset_ptr);
+
+protected:
+  /// All of the strings in the string table are contained in m_data.
+  llvm::StringRef m_data;
+};
+
+} // namespace lldb_private
+
+#endif // LLDB_CORE_DATAFILECACHE_H