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877ce944 AR |
1 | |
2 | /* | |
3 | * $Id$ | |
4 | * | |
5 | * DEBUG: section 5 Comm | |
6 | */ | |
7 | ||
8 | #include "DescriptorSet.h" | |
9 | ||
10 | // pre-allocates descriptor store and index for Squid_MaxFD descriptors | |
11 | DescriptorSet::DescriptorSet(): descriptors_(NULL), index_(NULL), | |
12 | capacity_(0), size_(0) | |
13 | { | |
14 | // we allocate once and never realloc, at least for now | |
15 | capacity_ = Squid_MaxFD; | |
16 | descriptors_ = new int[capacity_]; | |
17 | index_ = new int[capacity_]; | |
18 | ||
19 | // fill index with -1s to be able to say whether a descriptor is present | |
20 | // it is not essential to fill the descriptors, but it enables more checks | |
21 | for (int i = 0; i < capacity_; ++i) | |
22 | index_[i] = descriptors_[i] = -1; | |
23 | } | |
24 | ||
25 | DescriptorSet::~DescriptorSet() | |
26 | { | |
27 | delete[] descriptors_; | |
28 | delete[] index_; | |
29 | } | |
30 | ||
31 | /// adds if unique; returns true if added | |
32 | bool | |
33 | DescriptorSet::add(int fd) | |
34 | { | |
35 | assert(0 <= fd && fd < capacity_); // \todo: replace with Must() | |
36 | ||
37 | if (has(fd)) | |
38 | return false; // already have it | |
39 | ||
40 | assert(size_ < capacity_); // \todo: replace with Must() | |
41 | const int pos = size_++; | |
42 | index_[fd] = pos; | |
43 | descriptors_[pos] = fd; | |
44 | return true; // really added | |
45 | } | |
46 | ||
47 | /// deletes if there; returns true if deleted | |
48 | bool | |
49 | DescriptorSet::del(int fd) | |
50 | { | |
51 | assert(0 <= fd && fd < capacity_); // \todo: here and below, use Must() | |
52 | ||
53 | if (!has(fd)) | |
54 | return false; // we do not have it | |
55 | ||
56 | assert(!empty()); | |
57 | const int delPos = index_[fd]; | |
58 | assert(0 <= delPos && delPos < capacity_); | |
59 | ||
60 | // move the last descriptor to the deleted fd position | |
61 | // to avoid skipping deleted descriptors in pop() | |
62 | const int lastPos = size_-1; | |
63 | const int lastFd = descriptors_[lastPos]; | |
64 | assert(delPos <= lastPos); // may be the same | |
65 | descriptors_[delPos] = lastFd; | |
66 | index_[lastFd] = delPos; | |
67 | ||
68 | descriptors_[lastPos] = -1; | |
69 | index_[fd] = -1; | |
70 | --size_; | |
71 | ||
72 | return true; // really added | |
73 | } | |
74 | ||
75 | /// ejects one descriptor in unspecified order | |
76 | int | |
77 | DescriptorSet::pop() | |
78 | { | |
79 | assert(!empty()); | |
80 | const int lastPos =--size_; | |
81 | const int lastFd = descriptors_[lastPos]; | |
82 | assert(0 <= lastFd && lastFd < capacity_); | |
83 | ||
84 | // cleanup | |
85 | descriptors_[lastPos] = -1; | |
86 | index_[lastFd] = -1; | |
87 | ||
88 | return lastFd; | |
89 | } | |
90 | ||
91 | void | |
92 | DescriptorSet::print(std::ostream &os) const | |
93 | { | |
94 | // \todo add "name" if the set is used for more than just half-closed FDs | |
95 | os << size_ << " FDs"; | |
96 | } |