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1 | /* |
2 | * index.h: Manage indexes for agedu. |
3 | */ |
4 | |
5 | #include <sys/types.h> |
6 | |
7 | /* |
8 | * Given the size of an existing data file and the number of |
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9 | * entries required in the index, return the file size required to |
10 | * store the fixed initial fragment of the index before the |
11 | * indexbuild functions are invoked. |
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12 | */ |
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13 | off_t index_initial_size(off_t currentsize, int nodecount); |
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14 | |
15 | /* |
16 | * Build an index, given the address of a memory-mapped data file |
17 | * and the starting offset within it. |
18 | * |
19 | * trie_file structures passed to tf must of course be within the |
20 | * bounds of the memory-mapped file. |
21 | * |
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22 | * The "delta" parameter to indexbuild_new is filled in with the |
23 | * maximum size by which the index can ever grow in a single |
24 | * indexbuild_add call. This can be used, together with |
25 | * indexbuild_realsize, to detect when the index is about to get |
26 | * too big for its file and the file needs resizing. |
27 | * |
28 | * indexbuild_add adds a trie_file structure to the index. |
29 | * indexbuild_tag, called after that, causes the current state of |
30 | * the index to be preserved so that it can be queried later. It's |
31 | * idempotent, and will safely do nothing if called before |
32 | * indexbuild_add. |
33 | * |
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34 | * indexbuild_realsize returns the total amount of data _actually_ |
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35 | * written into the file, to allow it to be truncated afterwards, |
36 | * and to allow the caller of the indexbuild functions to know |
37 | * when the file is about to need to grow bigger during index |
38 | * building. |
39 | * |
40 | * indexbuild_rebase is used when the file has been |
41 | * re-memory-mapped at a different address (because it needs to |
42 | * grow). |
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43 | */ |
44 | typedef struct indexbuild indexbuild; |
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45 | indexbuild *indexbuild_new(void *t, off_t startoff, int nodecount, |
46 | size_t *delta); |
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47 | void indexbuild_add(indexbuild *ib, const struct trie_file *tf); |
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48 | void indexbuild_tag(indexbuild *ib); |
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49 | void indexbuild_rebase(indexbuild *ib, void *t); |
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50 | off_t indexbuild_realsize(indexbuild *ib); |
51 | void indexbuild_free(indexbuild *ib); |
52 | |
53 | /* |
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54 | * Check to see if a name index has an index tree root available |
55 | * (i.e. represents a directory rather than a file). |
56 | */ |
57 | int index_has_root(const void *t, int n); |
58 | |
59 | /* |
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60 | * Query an index to find the total size of records with name |
61 | * index strictly less than n, with atime less than at. |
62 | */ |
63 | unsigned long long index_query(const void *t, int n, unsigned long long at); |
64 | |
65 | /* |
66 | * Retrieve an order statistic from the index: given a fraction f, |
67 | * return an atime such that (at most) the requested fraction of |
68 | * the total data is older than it. |
69 | */ |
70 | unsigned long long index_order_stat(const void *t, double f); |