1 // Copyright 2011 The Kyua Authors.
2 // All rights reserved.
3 //
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5 // modification, are permitted provided that the following conditions are
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7 //
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9 // notice, this list of conditions and the following disclaimer.
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11 // notice, this list of conditions and the following disclaimer in the
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13 // * Neither the name of Google Inc. nor the names of its contributors
14 // may be used to endorse or promote products derived from this software
15 // without specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29 #include "store/metadata.hpp"
30
31 #include "store/exceptions.hpp"
32 #include "utils/format/macros.hpp"
33 #include "utils/sanity.hpp"
34 #include "utils/sqlite/database.hpp"
35 #include "utils/sqlite/exceptions.hpp"
36 #include "utils/sqlite/statement.ipp"
37
38 namespace sqlite = utils::sqlite;
39
40
41 namespace {
42
43
44 /// Fetches an integer column from a statement of the 'metadata' table.
45 ///
46 /// \param stmt The statement from which to get the column value.
47 /// \param column The name of the column to retrieve.
48 ///
49 /// \return The value of the column.
50 ///
51 /// \throw store::integrity_error If there is a problem fetching the value
52 /// caused by an invalid schema or data.
53 static int64_t
int64_column(sqlite::statement & stmt,const char * column)54 int64_column(sqlite::statement& stmt, const char* column)
55 {
56 int index;
57 try {
58 index = stmt.column_id(column);
59 } catch (const sqlite::invalid_column_error& e) {
60 UNREACHABLE_MSG("Invalid column specification; the SELECT statement "
61 "should have caught this");
62 }
63 if (stmt.column_type(index) != sqlite::type_integer)
64 throw store::integrity_error(F("The '%s' column in 'metadata' table "
65 "has an invalid type") % column);
66 return stmt.column_int64(index);
67 }
68
69
70 } // anonymous namespace
71
72
73 /// Constructs a new metadata object.
74 ///
75 /// \param schema_version_ The schema version.
76 /// \param timestamp_ The time at which this version was created.
metadata(const int schema_version_,const int64_t timestamp_)77 store::metadata::metadata(const int schema_version_, const int64_t timestamp_) :
78 _schema_version(schema_version_),
79 _timestamp(timestamp_)
80 {
81 }
82
83
84 /// Returns the timestamp of this entry.
85 ///
86 /// \return The timestamp in this metadata entry.
87 int64_t
timestamp(void) const88 store::metadata::timestamp(void) const
89 {
90 return _timestamp;
91 }
92
93
94 /// Returns the schema version.
95 ///
96 /// \return The schema version in this metadata entry.
97 int
schema_version(void) const98 store::metadata::schema_version(void) const
99 {
100 return _schema_version;
101 }
102
103
104 /// Reads the latest metadata entry from the database.
105 ///
106 /// \param db The database from which to read the metadata from.
107 ///
108 /// \return The current metadata of the database. It is not OK for the metadata
109 /// table to be empty, so this is guaranteed to return a value unless there is
110 /// an error.
111 ///
112 /// \throw store::integrity_error If the metadata in the database is empty,
113 /// has an invalid schema or its contents are bogus.
114 store::metadata
fetch_latest(sqlite::database & db)115 store::metadata::fetch_latest(sqlite::database& db)
116 {
117 try {
118 sqlite::statement stmt = db.create_statement(
119 "SELECT schema_version, timestamp FROM metadata "
120 "ORDER BY schema_version DESC LIMIT 1");
121 if (!stmt.step())
122 throw store::integrity_error("The 'metadata' table is empty");
123
124 const int schema_version_ =
125 static_cast< int >(int64_column(stmt, "schema_version"));
126 const int64_t timestamp_ = int64_column(stmt, "timestamp");
127
128 if (stmt.step())
129 UNREACHABLE_MSG("Got more than one result from a query that "
130 "does not permit this; any pragmas defined?");
131
132 return metadata(schema_version_, timestamp_);
133 } catch (const sqlite::error& e) {
134 throw store::integrity_error(F("Invalid metadata schema: %s") %
135 e.what());
136 }
137 }
138