sensordatastore.cpp 5.48 KB
Newer Older
1
2
3
4
5
6
7
/*
 * sensordatastore.cpp
 *
 *  Created on: Jul 24, 2013
 *      Author: Axel Auweter
 */

8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
/**
 * @mainpage
 * The DCDBLib library is a dynamic runtime library providing
 * functions to initialize and access the DCDB data store. It
 * is being used by the CollectAgent to handle insertion of
 * data and can be used by tools responsible for data analysis.
 *
 * Its main class is the SensorDataStore class which provides
 * functions to connect to the data store, initialize an empty
 * data base and to (TODO) retrieve data.
 *
 * For its internal handling, SensorDataStore relies on the
 * SensorDataStoreImpl class (which hides all private member
 * functions belonging to the SensorDataStore class from the
 * header that is used by programmers who link against this
 * library). Raw database functionality is abstracted into the
 * CassandraBackend class (to easy switching to other
 * key-value style databases in the future).
 *
27
 * To use the library in your client application, simply
28
29
30
31
 * include the sensordatastore.h header file and initialize
 * an object of the SensorDataStore class.
 */

Axel Auweter's avatar
Axel Auweter committed
32
33
#include <string>
#include <iostream>
34
35
#include <cstdint>
#include <cinttypes>
Axel Auweter's avatar
Axel Auweter committed
36

37
#include "cassandra.h"
Axel Auweter's avatar
Axel Auweter committed
38

39
#include "sensordatastore.h"
40
#include "sensordatastore_internal.h"
41
42
43
44
#include "connection.h"
#include "dcdbglobals.h"

#include "dcdbendian.h"
45

46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
/**
 * @details
 * Since we want high-performance inserts, we prepare the
 * insert CQL query in advance and only bind it on the actual
 * insert.
 */
void SensorDataStoreImpl::prepareInsert(uint64_t ttl)
{
  CassError rc = CASS_OK;
  CassFuture* future = NULL;
  const char* query;

  /*
   * Free the old prepared if necessary.
   */
  if (preparedInsert) {
      cass_prepared_free(preparedInsert);
  }

  char *queryBuf = NULL;
  if (ttl == 0) {
      query = "INSERT INTO dcdb.sensordata (sid, ts, value) VALUES (?, ?, ?);";
  }
  else {
      queryBuf = (char*)malloc(256);
      snprintf(queryBuf, 256, "INSERT INTO dcdb.sensordata (sid, ts, value) VALUES (?, ?, ?) USING TTL %" PRIu64 " ;", ttl);
      query = queryBuf;
  }

  future = cass_session_prepare(session, query);
  cass_future_wait(future);

  rc = cass_future_error_code(future);
  if (rc != CASS_OK) {
      connection->printError(future);
  } else {
      preparedInsert = cass_future_get_prepared(future);
  }

  cass_future_free(future);
  if (queryBuf) {
      free(queryBuf);
  }
}

91
92
93
94
95
96
97
98
99
100
101
102
103
104
/**
 * @details
 * To insert a sensor reading, the Rsvd field of the SensorId must
 * be filled with a time component that ensures that the maximum
 * number of 2^32 columns per key is not exceeded while still
 * allowing relatively easy retrieval of data.
 *
 * We achieve this by using a "week-stamp" (i.e. number of weeks
 * since Unix epoch) within the Rsvd field of the SensorId before
 * calling the Cassandra Backend to do the raw insert.
 *
 * Applications should not call this function directly, but
 * use the insert function provided by the SensorDataStore class.
 */
105
106
void SensorDataStoreImpl::insert(SensorId* sid, uint64_t ts, uint64_t value)
{
107
#if 0
108
109
110
  std::cout << "Inserting@SensorDataStoreImpl (" << sid->raw[0] << " " << sid->raw[1] << ", " << ts << ", " << value << ")" << std::endl;
#endif

111
  /* Calculate and insert week number */
112
  uint16_t week = ts / 604800000000000;
Axel Auweter's avatar
Axel Auweter committed
113
  sid->setRsvd(week);
114
115

  /* Insert into Cassandra */
Axel Auweter's avatar
Axel Auweter committed
116
  std::string key = sid->serialize();
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

  CassError rc = CASS_OK;
  CassStatement* statement = NULL;
  CassFuture *future = NULL;

  statement = cass_prepared_bind(preparedInsert);

  cass_statement_bind_bytes_by_name(statement, "sid", (cass_byte_t*)(key.c_str()), 16);
  cass_statement_bind_int64_by_name(statement, "ts", ts);
  cass_statement_bind_int64_by_name(statement, "value", value);

  future = cass_session_execute(session, statement);

  cass_future_wait(future);

  rc = cass_future_error_code(future);
  if (rc != CASS_OK) {
      connection->printError(future);
  }

  cass_future_free(future);
  cass_statement_free(statement);
139
140
}

141
142
/**
 * @details
143
144
 * This function updates the prepared statement for inserts
 * with the new TTL value.
145
 */
146
void SensorDataStoreImpl::setTTL(uint64_t ttl)
147
{
148
  prepareInsert(ttl);
149
150
}

151
152
/**
 * @details
153
154
155
 * This constructor sets the internal connection variable to
 * the externally provided DCDBConnection object and also
 * retrieves the CassSession pointer of the connection.
156
 */
157
SensorDataStoreImpl::SensorDataStoreImpl(DCDBConnection* conn)
158
{
159
160
  connection = conn;
  session = connection->getSessionHandle();
161
162
}

163
164
/**
 * @details
165
 * Due to the simplicity of the class, the destructor is left empty.
166
 */
167
SensorDataStoreImpl::~SensorDataStoreImpl()
168
{
169
  connection = nullptr;
170
171
}

172
173
174
175
176
177
/**
 * @details
 * Instead of doing the actual work, this function simply
 * forwards to the insert function of the SensorDataStoreImpl
 * class.
 */
178
179
180
181
182
void SensorDataStore::insert(SensorId* sid, uint64_t ts, uint64_t value)
{
    impl->insert(sid, ts, value);
}

183
184
/**
 * @details
185
186
187
 * Instead of doing the actual work, this function simply
 * forwards to the insert function of the SensorDataStoreImpl
 * class.
188
 */
189
void SensorDataStore::setTTL(uint64_t ttl)
190
{
191
    impl->setTTL(ttl);
192
193
}

194
195
/**
 * @details
196
197
 * This constructor allocates the implementation class which
 * holds the actual implementation of the class functionality.
198
 */
199
SensorDataStore::SensorDataStore(DCDBConnection* conn)
200
{
201
    impl = new SensorDataStoreImpl(conn);
202
203
}

204
205
206
207
208
/**
 * @details
 * The SensorDataStore desctructor deallocates the
 * SensorDataStoreImpl and CassandraBackend objects.
 */
209
210
SensorDataStore::~SensorDataStore()
{
211
212
213
  /* Clean up... */
  if (impl)
    delete impl;
214
}