GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/malloc_heap.cc
Date: 2025-08-31 02:39:21
Exec Total Coverage
Lines: 69 69 100.0%
Branches: 22 32 68.8%
Line Branch Exec Source
1 /**
2 * This file is part of the CernVM File System.
3 */
4
5
6 #include "malloc_heap.h"
7
8 #include <cassert>
9 #include <cstring>
10 #include <new>
11
12 #include "util/smalloc.h"
13
14 using namespace std; // NOLINT
15
16 3924759 void *MallocHeap::Allocate(uint64_t size, void *header, unsigned header_size) {
17
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 3924759 assert(size > 0);
18
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 3924759 assert(header_size <= size);
19 3924759 const uint64_t rounded_size = RoundUp8(size);
20 3924759 const int64_t real_size = rounded_size + sizeof(Tag);
21
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 3924759 if (gauge_ + real_size > capacity_)
22 147 return NULL;
23
24 3924612 unsigned char *new_block = heap_ + gauge_;
25 3924612 new (new_block) Tag(rounded_size);
26 3924612 new_block += sizeof(Tag);
27 3924612 memcpy(new_block, header, header_size);
28 3924612 gauge_ += real_size;
29 3924612 stored_ += rounded_size;
30 3924612 num_blocks_++;
31 3924612 return new_block;
32 }
33
34
35 221 void MallocHeap::Compact() {
36
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 221 if (gauge_ == 0)
37 37 return;
38
39 // Not really a tag, just the top memory address
40 184 Tag *heap_top = reinterpret_cast<Tag *>(heap_ + gauge_);
41 184 Tag *current_tag = reinterpret_cast<Tag *>(heap_);
42 184 Tag *next_tag = current_tag->JumpToNext();
43 // Move a sliding window of two blocks over the heap and compact where
44 // possible
45
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 5881347 while (next_tag < heap_top) {
46
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 5881163 if (current_tag->IsFree()) {
47
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 3886394 if (next_tag->IsFree()) {
48 // Adjacent free blocks, merge and try again
49 1928588 current_tag->size -= sizeof(Tag) + next_tag->GetSize();
50 1928588 next_tag = next_tag->JumpToNext();
51 } else {
52 // Free block followed by a reserved block, move memory and create a
53 // new free tag at the end of the moved block
54 1957806 const int64_t free_space = current_tag->size;
55 1957806 current_tag->size = next_tag->size;
56 1957806 memmove(current_tag->GetBlock(), next_tag->GetBlock(),
57 next_tag->GetSize());
58
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 1957806 (*callback_ptr_)(BlockPtr(current_tag->GetBlock()));
59 1957806 next_tag = current_tag->JumpToNext();
60 1957806 next_tag->size = free_space;
61 }
62 } else {
63 // Current block allocated, move on
64 1994769 current_tag = next_tag;
65 1994769 next_tag = next_tag->JumpToNext();
66 }
67 }
68
69 184 gauge_ = (reinterpret_cast<unsigned char *>(current_tag) - heap_);
70
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 184 if (!current_tag->IsFree())
71 37 gauge_ += sizeof(Tag) + current_tag->GetSize();
72 }
73
74
75 74 void *MallocHeap::Expand(void *block, uint64_t new_size) {
76 74 const uint64_t old_size = GetSize(block);
77
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 74 assert(old_size <= new_size);
78 74 void *new_block = Allocate(new_size, block, old_size);
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 74 if (new_block != NULL)
80 74 MarkFree(block);
81 74 return new_block;
82 }
83
84
85 73944 bool MallocHeap::HasSpaceFor(uint64_t nbytes) {
86 73944 return RoundUp8(gauge_ + nbytes + sizeof(Tag)) <= capacity_;
87 }
88
89
90 1928809 void MallocHeap::MarkFree(void *block) {
91 1928809 Tag *tag = reinterpret_cast<Tag *>(block) - 1;
92
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 1928809 assert(tag->size > 0);
93 1928809 tag->size = -(tag->size);
94 1928809 stored_ -= tag->GetSize();
95 1928809 num_blocks_--;
96 // TODO(jblomer): if MarkFree() takes place at the top of the heap, one could
97 // move back the gauge_ pointer. If this is an optimization or unnecessary
98 // extra work depends on how the MallocHeap is used.
99 1928809 }
100
101
102 1846300 uint64_t MallocHeap::GetSize(void *block) {
103 1846300 Tag *tag = reinterpret_cast<Tag *>(block) - 1;
104
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 1846300 assert(tag->size > 0);
105 1846300 return tag->size;
106 }
107
108
109 268 MallocHeap::MallocHeap(uint64_t capacity, CallbackPtr callback_ptr)
110 268 : callback_ptr_(callback_ptr)
111 268 , capacity_(capacity)
112 268 , gauge_(0)
113 268 , stored_(0)
114 268 , num_blocks_(0) {
115
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 268 assert(capacity_ > kMinCapacity);
116 // Ensure 8-byte alignment
117
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 268 assert((capacity_ % 8) == 0);
118 268 heap_ = reinterpret_cast<unsigned char *>(sxmmap(capacity));
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 268 assert(uintptr_t(heap_) % 8 == 0);
120 268 }
121
122
123 267 MallocHeap::~MallocHeap() { sxunmap(heap_, capacity_); }
124