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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2001,2008 Oracle. All rights reserved.
*
* $Id: RepQuoteExample.cpp,v 1.21 2008/04/28 02:59:56 alexg Exp $
*/
/*
* In this application, we specify all communication via the command line. In
* a real application, we would expect that information about the other sites
* in the system would be maintained in some sort of configuration file. The
* critical part of this interface is that we assume at startup that we can
* find out
* 1) what host/port we wish to listen on for connections,
* 2) a (possibly empty) list of other sites we should attempt to connect
* to; and
* 3) what our Berkeley DB home environment is.
*
* These pieces of information are expressed by the following flags.
* -m host:port (required; m stands for me)
* -o host:port (optional; o stands for other; any number of these may be
* specified)
* -h home directory
* -n nsites (optional; number of sites in replication group; defaults to 0
* in which case we try to dynamically compute the number of sites in
* the replication group)
* -p priority (optional: defaults to 100)
*/
#include <iostream>
#include <string>
#include <sstream>
#include <db_cxx.h>
#include "RepConfigInfo.h"
#include "dbc_auto.h"
using std::cout;
using std::cin;
using std::cerr;
using std::endl;
using std::flush;
using std::istream;
using std::istringstream;
using std::string;
using std::getline;
#define CACHESIZE (10 * 1024 * 1024)
#define DATABASE "quote.db"
const char *progname = "excxx_repquote";
#include <errno.h>
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
extern "C" {
extern int getopt(int, char * const *, const char *);
extern char *optarg;
}
#endif
// Struct used to store information in Db app_private field.
typedef struct {
bool is_master;
} APP_DATA;
static void log(char *);
class RepQuoteExample {
public:
RepQuoteExample();
void init(RepConfigInfo* config);
void doloop();
int terminate();
static void event_callback(DbEnv * dbenv, u_int32_t which, void *info);
private:
// disable copy constructor.
RepQuoteExample(const RepQuoteExample &);
void operator = (const RepQuoteExample &);
// internal data members.
APP_DATA app_data;
RepConfigInfo *app_config;
DbEnv cur_env;
// private methods.
void print_stocks(Db *dbp);
void prompt();
};
class DbHolder {
public:
DbHolder(DbEnv *env) : env(env) {
dbp = 0;
}
~DbHolder() {
try {
close();
} catch (...) {
// Ignore: this may mean another exception is pending
}
}
bool ensure_open(bool creating) {
if (dbp)
return (true);
dbp = new Db(env, 0);
dbp->set_pagesize(512);
u_int32_t flags = DB_AUTO_COMMIT;
if (creating)
flags |= DB_CREATE;
try {
dbp->open(NULL, DATABASE, NULL, DB_BTREE, flags, 0);
return (true);
} catch (DbDeadlockException e) {
} catch (DbRepHandleDeadException e) {
} catch (DbException e) {
if (e.get_errno() == DB_REP_LOCKOUT) {
// Just fall through.
} else if (e.get_errno() == ENOENT && !creating) {
// Provide a bit of extra explanation.
//
log("Stock DB does not yet exist");
} else
throw;
}
// (All retryable errors fall through to here.)
//
log("please retry the operation");
close();
return (false);
}
void close() {
if (dbp) {
try {
dbp->close(0);
delete dbp;
dbp = 0;
} catch (...) {
delete dbp;
dbp = 0;
throw;
}
}
}
operator Db *() {
return dbp;
}
Db *operator->() {
return dbp;
}
private:
Db *dbp;
DbEnv *env;
};
class StringDbt : public Dbt {
public:
#define GET_STRING_OK 0
#define GET_STRING_INVALID_PARAM 1
#define GET_STRING_SMALL_BUFFER 2
#define GET_STRING_EMPTY_DATA 3
int get_string(char **buf, size_t buf_len)
{
size_t copy_len;
int ret = GET_STRING_OK;
if (buf == NULL) {
cerr << "Invalid input buffer to get_string" << endl;
return GET_STRING_INVALID_PARAM;
}
// make sure the string is null terminated.
memset(*buf, 0, buf_len);
// if there is no string, just return.
if (get_data() == NULL || get_size() == 0)
return GET_STRING_OK;
if (get_size() >= buf_len) {
ret = GET_STRING_SMALL_BUFFER;
copy_len = buf_len - 1; // save room for a terminator.
} else
copy_len = get_size();
memcpy(*buf, get_data(), copy_len);
return ret;
}
size_t get_string_length()
{
if (get_size() == 0)
return 0;
return strlen((char *)get_data());
}
void set_string(char *string)
{
set_data(string);
set_size((u_int32_t)strlen(string));
}
StringDbt(char *string) :
Dbt(string, (u_int32_t)strlen(string)) {};
StringDbt() : Dbt() {};
~StringDbt() {};
// Don't add extra data to this sub-class since we want it to remain
// compatible with Dbt objects created internally by Berkeley DB.
};
RepQuoteExample::RepQuoteExample() : app_config(0), cur_env(0) {
app_data.is_master = 0; // assume I start out as client
}
void RepQuoteExample::init(RepConfigInfo *config) {
app_config = config;
cur_env.set_app_private(&app_data);
cur_env.set_errfile(stderr);
cur_env.set_errpfx(progname);
cur_env.set_event_notify(event_callback);
cur_env.repmgr_set_ack_policy(DB_REPMGR_ACKS_ALL);
cur_env.repmgr_set_local_site(app_config->this_host.host,
app_config->this_host.port, 0);
for ( REP_HOST_INFO *cur = app_config->other_hosts; cur != NULL;
cur = cur->next) {
cur_env.repmgr_add_remote_site(cur->host, cur->port,
NULL, cur->peer ? DB_REPMGR_PEER : 0);
}
if (app_config->totalsites > 0)
cur_env.rep_set_nsites(app_config->totalsites);
cur_env.rep_set_priority(app_config->priority);
/*
* We can now open our environment, although we're not ready to
* begin replicating. However, we want to have a dbenv around
* so that we can send it into any of our message handlers.
*/
cur_env.set_cachesize(0, CACHESIZE, 0);
cur_env.set_flags(DB_TXN_NOSYNC, 1);
cur_env.open(app_config->home, DB_CREATE | DB_RECOVER |
DB_THREAD | DB_INIT_REP | DB_INIT_LOCK | DB_INIT_LOG |
DB_INIT_MPOOL | DB_INIT_TXN, 0);
if (app_config->verbose)
cur_env.set_verbose(DB_VERB_REPLICATION, 1);
cur_env.repmgr_start(3, app_config->start_policy);
}
int RepQuoteExample::terminate() {
try {
/*
* We have used the DB_TXN_NOSYNC environment flag for
* improved performance without the usual sacrifice of
* transactional durability, as discussed in the
* "Transactional guarantees" page of the Reference
* Guide: if one replication site crashes, we can
* expect the data to exist at another site. However,
* in case we shut down all sites gracefully, we push
* out the end of the log here so that the most
* recent transactions don't mysteriously disappear.
*/
cur_env.log_flush(NULL);
cur_env.close(0);
} catch (DbException dbe) {
cout << "error closing environment: " << dbe.what() << endl;
}
return 0;
}
void RepQuoteExample::prompt() {
cout << "QUOTESERVER";
if (!app_data.is_master)
cout << "(read-only)";
cout << "> " << flush;
}
void log(char *msg) {
cerr << msg << endl;
}
// Simple command-line user interface:
// - enter "<stock symbol> <price>" to insert or update a record in the
// database;
// - just press Return (i.e., blank input line) to print out the contents of
// the database;
// - enter "quit" or "exit" to quit.
//
void RepQuoteExample::doloop() {
DbHolder dbh(&cur_env);
string input;
while (prompt(), getline(cin, input)) {
istringstream is(input);
string token1, token2;
// Read 0, 1 or 2 tokens from the input.
//
int count = 0;
if (is >> token1) {
count++;
if (is >> token2)
count++;
}
if (count == 1) {
if (token1 == "exit" || token1 == "quit")
break;
else {
log("Format: <stock> <price>");
continue;
}
}
// Here we know count is either 0 or 2, so we're about to try a
// DB operation.
//
if (!dbh.ensure_open(app_data.is_master))
continue;
try {
if (count == 0)
print_stocks(dbh);
else if (!app_data.is_master)
log("Can't update at client");
else {
const char *symbol = token1.c_str();
StringDbt key(const_cast<char*>(symbol));
const char *price = token2.c_str();
StringDbt data(const_cast<char*>(price));
dbh->put(NULL, &key, &data, 0);
}
} catch (DbDeadlockException e) {
log("please retry the operation");
dbh.close();
} catch (DbRepHandleDeadException e) {
log("please retry the operation");
dbh.close();
} catch (DbException e) {
if (e.get_errno() == DB_REP_LOCKOUT) {
log("please retry the operation");
dbh.close();
} else
throw;
}
}
dbh.close();
}
void RepQuoteExample::event_callback(DbEnv* dbenv, u_int32_t which, void *info)
{
APP_DATA *app = (APP_DATA*)dbenv->get_app_private();
info = NULL; /* Currently unused. */
switch (which) {
case DB_EVENT_REP_MASTER:
app->is_master = 1;
break;
case DB_EVENT_REP_CLIENT:
app->is_master = 0;
break;
case DB_EVENT_REP_STARTUPDONE: /* FALLTHROUGH */
case DB_EVENT_REP_NEWMASTER:
case DB_EVENT_REP_PERM_FAILED:
// I don't care about this one, for now.
break;
default:
dbenv->errx("ignoring event %d", which);
}
}
void RepQuoteExample::print_stocks(Db *dbp) {
StringDbt key, data;
#define MAXKEYSIZE 10
#define MAXDATASIZE 20
char keybuf[MAXKEYSIZE + 1], databuf[MAXDATASIZE + 1];
char *kbuf, *dbuf;
memset(&key, 0, sizeof(key));
memset(&data, 0, sizeof(data));
kbuf = keybuf;
dbuf = databuf;
DbcAuto dbc(dbp, 0, 0);
cout << "\tSymbol\tPrice" << endl
<< "\t======\t=====" << endl;
for (int ret = dbc->get(&key, &data, DB_FIRST);
ret == 0;
ret = dbc->get(&key, &data, DB_NEXT)) {
key.get_string(&kbuf, MAXKEYSIZE);
data.get_string(&dbuf, MAXDATASIZE);
cout << "\t" << keybuf << "\t" << databuf << endl;
}
cout << endl << flush;
dbc.close();
}
static void usage() {
cerr << "usage: " << progname << endl
<< "[-h home][-o host:port][-m host:port][-f host:port]"
<< "[-n nsites][-p priority]" << endl;
cerr << "\t -m host:port (required; m stands for me)" << endl
<< "\t -o host:port (optional; o stands for other; any "
<< "number of these may be specified)" << endl
<< "\t -h home directory" << endl
<< "\t -n nsites (optional; number of sites in replication "
<< "group; defaults to 0" << endl
<< "\t in which case we try to dynamically compute the "
<< "number of sites in" << endl
<< "\t the replication group)" << endl
<< "\t -p priority (optional: defaults to 100)" << endl;
exit(EXIT_FAILURE);
}
int main(int argc, char **argv) {
RepConfigInfo config;
char ch, *portstr, *tmphost;
int tmpport;
bool tmppeer;
// Extract the command line parameters
while ((ch = getopt(argc, argv, "Cf:h:Mm:n:o:p:v")) != EOF) {
tmppeer = false;
switch (ch) {
case 'C':
config.start_policy = DB_REP_CLIENT;
break;
case 'h':
config.home = optarg;
break;
case 'M':
config.start_policy = DB_REP_MASTER;
break;
case 'm':
config.this_host.host = strtok(optarg, ":");
if ((portstr = strtok(NULL, ":")) == NULL) {
cerr << "Bad host specification." << endl;
usage();
}
config.this_host.port = (unsigned short)atoi(portstr);
config.got_listen_address = true;
break;
case 'n':
config.totalsites = atoi(optarg);
break;
case 'f':
tmppeer = true; // FALLTHROUGH
case 'o':
tmphost = strtok(optarg, ":");
if ((portstr = strtok(NULL, ":")) == NULL) {
cerr << "Bad host specification." << endl;
usage();
}
tmpport = (unsigned short)atoi(portstr);
config.addOtherHost(tmphost, tmpport, tmppeer);
break;
case 'p':
config.priority = atoi(optarg);
break;
case 'v':
config.verbose = true;
break;
case '?':
default:
usage();
}
}
// Error check command line.
if ((!config.got_listen_address) || config.home == NULL)
usage();
RepQuoteExample runner;
try {
runner.init(&config);
runner.doloop();
} catch (DbException dbe) {
cerr << "Caught an exception during initialization or"
<< " processing: " << dbe.what() << endl;
}
runner.terminate();
return 0;
}
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