1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
7 #include "SharedStringMap.h"
9 #include "MemMapSnapshot.h"
10 #include "ScriptPreloader-inl.h"
12 #include "mozilla/BinarySearch.h"
13 #include "mozilla/ipc/FileDescriptor.h"
15 using namespace mozilla::loader
;
23 static constexpr uint32_t kSharedStringMapMagic
= 0x9e3779b9;
25 static inline size_t GetAlignmentOffset(size_t aOffset
, size_t aAlign
) {
26 auto mod
= aOffset
% aAlign
;
27 return mod
? aAlign
- mod
: 0;
30 SharedStringMap::SharedStringMap(const FileDescriptor
& aMapFile
,
32 auto result
= mMap
.initWithHandle(aMapFile
, aMapSize
);
33 MOZ_RELEASE_ASSERT(result
.isOk());
34 MOZ_RELEASE_ASSERT(GetHeader().mMagic
== kSharedStringMapMagic
);
35 // We return literal nsStrings and nsCStrings pointing to the mapped data,
36 // which means that we may still have references to the mapped data even
37 // after this instance is destroyed. That means that we need to keep the
38 // mapping alive until process shutdown, in order to be safe.
42 SharedStringMap::SharedStringMap(SharedStringMapBuilder
&& aBuilder
) {
43 auto result
= aBuilder
.Finalize(mMap
);
44 MOZ_RELEASE_ASSERT(result
.isOk());
45 MOZ_RELEASE_ASSERT(GetHeader().mMagic
== kSharedStringMapMagic
);
49 mozilla::ipc::FileDescriptor
SharedStringMap::CloneFileDescriptor() const {
50 return mMap
.cloneHandle();
53 bool SharedStringMap::Has(const nsCString
& aKey
) {
55 return Find(aKey
, &index
);
58 bool SharedStringMap::Get(const nsCString
& aKey
, nsAString
& aValue
) {
59 const auto& entries
= Entries();
62 if (!Find(aKey
, &index
)) {
66 aValue
.Assign(ValueTable().Get(entries
[index
].mValue
));
70 bool SharedStringMap::Find(const nsCString
& aKey
, size_t* aIndex
) {
71 const auto& keys
= KeyTable();
73 return BinarySearchIf(
74 Entries(), 0, EntryCount(),
75 [&](const Entry
& aEntry
) { return Compare(aKey
, keys
.Get(aEntry
.mKey
)); },
79 void SharedStringMapBuilder::Add(const nsCString
& aKey
,
80 const nsString
& aValue
) {
81 mEntries
.InsertOrUpdate(aKey
,
82 Entry
{mKeyTable
.Add(aKey
), mValueTable
.Add(aValue
)});
85 Result
<Ok
, nsresult
> SharedStringMapBuilder::Finalize(
86 loader::AutoMemMap
& aMap
) {
87 using Header
= SharedStringMap::Header
;
89 MOZ_ASSERT(mEntries
.Count() == mKeyTable
.Count());
91 auto keys
= ToTArray
<nsTArray
<nsCString
>>(mEntries
.Keys());
94 Header header
= {kSharedStringMapMagic
, uint32_t(keys
.Length())};
96 size_t offset
= sizeof(header
);
97 offset
+= GetAlignmentOffset(offset
, alignof(Header
));
99 offset
+= keys
.Length() * sizeof(SharedStringMap::Entry
);
101 header
.mKeyStringsOffset
= offset
;
102 header
.mKeyStringsSize
= mKeyTable
.Size();
104 offset
+= header
.mKeyStringsSize
;
106 GetAlignmentOffset(offset
, alignof(decltype(mValueTable
)::ElemType
));
108 header
.mValueStringsOffset
= offset
;
109 header
.mValueStringsSize
= mValueTable
.Size();
111 offset
+= header
.mValueStringsSize
;
114 MOZ_TRY(mem
.Init(offset
));
116 auto headerPtr
= mem
.Get
<Header
>();
117 headerPtr
[0] = header
;
119 auto* entry
= reinterpret_cast<Entry
*>(&headerPtr
[1]);
120 for (auto& key
: keys
) {
121 *entry
++ = mEntries
.Get(key
);
124 auto ptr
= mem
.Get
<uint8_t>();
126 mKeyTable
.Write({&ptr
[header
.mKeyStringsOffset
], header
.mKeyStringsSize
});
129 {&ptr
[header
.mValueStringsOffset
], header
.mValueStringsSize
});
135 return mem
.Finalize(aMap
);
138 } // namespace dom::ipc
139 } // namespace mozilla