1 files changed, 123 insertions, 0 deletions
diff --git a/llvm/lib/CAS/DatabaseFile.cpp b/llvm/lib/CAS/DatabaseFile.cpp
new file mode 100644
index 0000000..db8ce1d
--- /dev/null
+++ b/llvm/lib/CAS/DatabaseFile.cpp
@@ -0,0 +1,123 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file This file implements the common abstractions for CAS database file.
+///
+//===----------------------------------------------------------------------===//
+
+#include "DatabaseFile.h"
+
+using namespace llvm;
+using namespace llvm::cas;
+using namespace llvm::cas::ondisk;
+
+Error ondisk::createTableConfigError(std::errc ErrC, StringRef Path,
+                                     StringRef TableName, const Twine &Msg) {
+  return createStringError(make_error_code(ErrC),
+                           Path + "[" + TableName + "]: " + Msg);
+}
+
+Error ondisk::checkTable(StringRef Label, size_t Expected, size_t Observed,
+                         StringRef Path, StringRef TrieName) {
+  if (Expected == Observed)
+    return Error::success();
+  return createTableConfigError(std::errc::invalid_argument, Path, TrieName,
+                                "mismatched " + Label +
+                                    " (expected: " + Twine(Expected) +
+                                    ", observed: " + Twine(Observed) + ")");
+}
+
+Expected<DatabaseFile>
+DatabaseFile::create(const Twine &Path, uint64_t Capacity,
+                     function_ref<Error(DatabaseFile &)> NewDBConstructor) {
+  // Constructor for if the file doesn't exist.
+  auto NewFileConstructor = [&](MappedFileRegionArena &Alloc) -> Error {
+    if (Alloc.capacity() <
+        sizeof(Header) + sizeof(MappedFileRegionArena::Header))
+      return createTableConfigError(std::errc::argument_out_of_domain,
+                                    Path.str(), "datafile",
+                                    "Allocator too small for header");
+    (void)new (Alloc.data()) Header{getMagic(), getVersion(), {0}};
+    DatabaseFile DB(Alloc);
+    return NewDBConstructor(DB);
+  };
+
+  // Get or create the file.
+  MappedFileRegionArena Alloc;
+  if (Error E = MappedFileRegionArena::create(Path, Capacity, sizeof(Header),
+                                              NewFileConstructor)
+                    .moveInto(Alloc))
+    return std::move(E);
+
+  return DatabaseFile::get(
+      std::make_unique<MappedFileRegionArena>(std::move(Alloc)));
+}
+
+Error DatabaseFile::addTable(TableHandle Table) {
+  assert(Table);
+  assert(&Table.getRegion() == &getRegion());
+  int64_t ExistingRootOffset = 0;
+  const int64_t NewOffset =
+      reinterpret_cast<const char *>(&Table.getHeader()) - getRegion().data();
+  if (H->RootTableOffset.compare_exchange_strong(ExistingRootOffset, NewOffset))
+    return Error::success();
+
+  // Silently ignore attempts to set the root to itself.
+  if (ExistingRootOffset == NewOffset)
+    return Error::success();
+
+  // Return an proper error message.
+  TableHandle Root(getRegion(), ExistingRootOffset);
+  if (Root.getName() == Table.getName())
+    return createStringError(
+        make_error_code(std::errc::not_supported),
+        "collision with existing table of the same name '" + Table.getName() +
+            "'");
+
+  return createStringError(make_error_code(std::errc::not_supported),
+                           "cannot add new table '" + Table.getName() +
+                               "'"
+                               " to existing root '" +
+                               Root.getName() + "'");
+}
+
+std::optional<TableHandle> DatabaseFile::findTable(StringRef Name) {
+  int64_t RootTableOffset = H->RootTableOffset.load();
+  if (!RootTableOffset)
+    return std::nullopt;
+
+  TableHandle Root(getRegion(), RootTableOffset);
+  if (Root.getName() == Name)
+    return Root;
+
+  return std::nullopt;
+}
+
+Error DatabaseFile::validate(MappedFileRegion &Region) {
+  if (Region.size() < sizeof(Header))
+    return createStringError(std::errc::invalid_argument,
+                             "database: missing header");
+
+  // Check the magic and version.
+  auto *H = reinterpret_cast<Header *>(Region.data());
+  if (H->Magic != getMagic())
+    return createStringError(std::errc::invalid_argument,
+                             "database: bad magic");
+  if (H->Version != getVersion())
+    return createStringError(std::errc::invalid_argument,
+                             "database: wrong version");
+
+  auto *MFH = reinterpret_cast<MappedFileRegionArena::Header *>(Region.data() +
+                                                                sizeof(Header));
+  // Check the bump-ptr, which should point past the header.
+  if (MFH->BumpPtr.load() < (int64_t)sizeof(Header))
+    return createStringError(std::errc::invalid_argument,
+                             "database: corrupt bump-ptr");
+
+  return Error::success();
+}