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Examples

Simon Ninon edited this page Nov 26, 2017 · 11 revisions

Redis Client

// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <[email protected]>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <cpp_redis/cpp_redis>

#include <iostream>

#ifdef _WIN32
#include <Winsock2.h>
#endif /* _WIN32 */

int
main(void) {
#ifdef _WIN32
  //! Windows netword DLL init
  WORD version = MAKEWORD(2, 2);
  WSADATA data;

  if (WSAStartup(version, &data) != 0) {
    std::cerr << "WSAStartup() failure" << std::endl;
    return -1;
  }
#endif /* _WIN32 */

  //! Enable logging
  cpp_redis::active_logger = std::unique_ptr<cpp_redis::logger>(new cpp_redis::logger);

  cpp_redis::client client;

  client.connect("127.0.0.1", 6379, [](const std::string& host, std::size_t port, cpp_redis::client::connect_state status) {
    if (status == cpp_redis::client::connect_state::dropped) {
      std::cout << "client disconnected from " << host << ":" << port << std::endl;
    }
  });

  // same as client.send({ "SET", "hello", "42" }, ...)
  client.set("hello", "42", [](cpp_redis::reply& reply) {
    std::cout << "set hello 42: " << reply << std::endl;
    // if (reply.is_string())
    //   do_something_with_string(reply.as_string())
  });

  // same as client.send({ "DECRBY", "hello", 12 }, ...)
  client.decrby("hello", 12, [](cpp_redis::reply& reply) {
    std::cout << "decrby hello 12: " << reply << std::endl;
    // if (reply.is_integer())
    //   do_something_with_integer(reply.as_integer())
  });

  // same as client.send({ "GET", "hello" }, ...)
  client.get("hello", [](cpp_redis::reply& reply) {
    std::cout << "get hello: " << reply << std::endl;
    // if (reply.is_string())
    //   do_something_with_string(reply.as_string())
  });

  // commands are pipelined and only sent when client.commit() is called
  // client.commit();

  // synchronous commit, no timeout
  client.sync_commit();

// synchronous commit, timeout
// client.sync_commit(std::chrono::milliseconds(100));

#ifdef _WIN32
  WSACleanup();
#endif /* _WIN32 */

  return 0;
}

Redis Subscriber

// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <[email protected]>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <cpp_redis/cpp_redis>
#include <tacopie/tacopie>

#include <condition_variable>
#include <iostream>
#include <mutex>
#include <signal.h>

#ifdef _WIN32
#include <Winsock2.h>
#endif /* _WIN32 */

std::condition_variable should_exit;

void
sigint_handler(int) {
  should_exit.notify_all();
}

int
main(void) {
#ifdef _WIN32
  //! Windows netword DLL init
  WORD version = MAKEWORD(2, 2);
  WSADATA data;

  if (WSAStartup(version, &data) != 0) {
    std::cerr << "WSAStartup() failure" << std::endl;
    return -1;
  }
#endif /* _WIN32 */

  //! Enable logging
  cpp_redis::active_logger = std::unique_ptr<cpp_redis::logger>(new cpp_redis::logger);

  cpp_redis::subscriber sub;


  sub.connect("127.0.0.1", 6379, [](const std::string& host, std::size_t port, cpp_redis::subscriber::connect_state status) {
    if (status == cpp_redis::subscriber::connect_state::dropped) {
      std::cout << "client disconnected from " << host << ":" << port << std::endl;
      should_exit.notify_all();
    }
  });

  //! authentication if server-server requires it
  // sub.auth("some_password", [](const cpp_redis::reply& reply) {
  //   if (reply.is_error()) { std::cerr << "Authentication failed: " << reply.as_string() << std::endl; }
  //   else {
  //     std::cout << "successful authentication" << std::endl;
  //   }
  // });

  sub.subscribe("some_chan", [](const std::string& chan, const std::string& msg) {
    std::cout << "MESSAGE " << chan << ": " << msg << std::endl;
  });
  sub.psubscribe("*", [](const std::string& chan, const std::string& msg) {
    std::cout << "PMESSAGE " << chan << ": " << msg << std::endl;
  });
  sub.commit();

  signal(SIGINT, &sigint_handler);
  std::mutex mtx;
  std::unique_lock<std::mutex> l(mtx);
  should_exit.wait(l);

#ifdef _WIN32
  WSACleanup();
#endif /* _WIN32 */

  return 0;
}

Future Client

// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <[email protected]>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <cpp_redis/cpp_redis>

#include <iostream>

#ifdef _WIN32
#include <Winsock2.h>
#endif /* _WIN32 */

int
main(void) {
#ifdef _WIN32
  //! Windows netword DLL init
  WORD version = MAKEWORD(2, 2);
  WSADATA data;

  if (WSAStartup(version, &data) != 0) {
    std::cerr << "WSAStartup() failure" << std::endl;
    return -1;
  }
#endif /* _WIN32 */

  //! Enable logging
  cpp_redis::active_logger = std::unique_ptr<cpp_redis::logger>(new cpp_redis::logger);

  cpp_redis::client client;

  client.connect("127.0.0.1", 6379, [](const std::string& host, std::size_t port, cpp_redis::client::connect_state status) {
    if (status == cpp_redis::client::connect_state::dropped) {
      std::cout << "client disconnected from " << host << ":" << port << std::endl;
    }
  });

  //! Set a value
  auto set    = client.set("hello", "42");
  auto decrby = client.decrby("hello", 12);
  auto get    = client.get("hello");

  // commands are pipelined and only sent when client.commit() is called
  // client.commit();

  // synchronous commit, no timeout
  client.sync_commit();

  // synchronous commit, timeout
  // client.sync_commit(std::chrono::milliseconds(100));

  std::cout << "set 'hello' 42: " << set.get() << std::endl;

  cpp_redis::reply r = decrby.get();
  if (r.is_integer())
    std::cout << "After 'hello' decrement by 12: " << r.as_integer() << std::endl;

  std::cout << "get 'hello': " << get.get() << std::endl;

#ifdef _WIN32
  WSACleanup();
#endif /* _WIN32 */

  return 0;
}

Logger

// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <[email protected]>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <cpp_redis/cpp_redis>

#include <iostream>

class my_logger : public cpp_redis::logger_iface {
public:
  //! ctor & dtor
  my_logger(void)  = default;
  ~my_logger(void) = default;

  //! copy ctor & assignment operator
  my_logger(const my_logger&) = default;
  my_logger& operator=(const my_logger&) = default;

public:
  void
  debug(const std::string& msg, const std::string& file, std::size_t line) {
    std::cout << "debug: " << msg << " @ " << file << ":" << line << std::endl;
  }

  void
  info(const std::string& msg, const std::string& file, std::size_t line) {
    std::cout << "info: " << msg << " @ " << file << ":" << line << std::endl;
  }

  void
  warn(const std::string& msg, const std::string& file, std::size_t line) {
    std::cout << "warn: " << msg << " @ " << file << ":" << line << std::endl;
  }

  void
  error(const std::string& msg, const std::string& file, std::size_t line) {
    std::cerr << "error: " << msg << " @ " << file << ":" << line << std::endl;
  }
};


int
main(void) {
  //! By default, no logging
  //! Force logger call, just for the example (you will never have to do that by yourself)
  std::cout << "By default: no logging" << std::endl;
  __CPP_REDIS_LOG(debug, "This is a debug message");
  __CPP_REDIS_LOG(info, "This is an info message");
  __CPP_REDIS_LOG(warn, "This is a warn message");
  __CPP_REDIS_LOG(error, "This is an error message");
  std::cout << std::endl;

  //! Use the default logger, provided with the library
  cpp_redis::active_logger = std::unique_ptr<cpp_redis::logger>(new cpp_redis::logger);
  //! Force logger call, just for the example (you will never have to do that by yourself)
  std::cout << "With the library provided logger" << std::endl;
  __CPP_REDIS_LOG(debug, "This is a debug message");
  __CPP_REDIS_LOG(info, "This is an info message");
  __CPP_REDIS_LOG(warn, "This is a warn message");
  __CPP_REDIS_LOG(error, "This is an error message");
  std::cout << std::endl;

  //! Use your custom logger
  cpp_redis::active_logger = std::unique_ptr<my_logger>(new my_logger);
  //! Force logger call, just for the example (you will never have to do that by yourself)
  std::cout << "With an example of custom logger" << std::endl;
  __CPP_REDIS_LOG(debug, "This is a debug message");
  __CPP_REDIS_LOG(info, "This is an info message");
  __CPP_REDIS_LOG(warn, "This is a warn message");
  __CPP_REDIS_LOG(error, "This is an error message");
  std::cout << std::endl;

  return 0;
}

Kill

// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <[email protected]>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <cpp_redis/cpp_redis>

#include <iostream>
#include <sstream>

#ifdef _WIN32
#include <Winsock2.h>
#endif /* _WIN32 */

int
main(void) {
#ifdef _WIN32
  //! Windows netword DLL init
  WORD version = MAKEWORD(2, 2);
  WSADATA data;

  if (WSAStartup(version, &data) != 0) {
    std::cerr << "WSAStartup() failure" << std::endl;
    return -1;
  }
#endif /* _WIN32 */

  cpp_redis::client client;

  client.connect("127.0.0.1", 6379, [](const std::string& host, std::size_t port, cpp_redis::client::connect_state status) {
    if (status == cpp_redis::client::connect_state::dropped) {
      std::cout << "client disconnected from " << host << ":" << port << std::endl;
    }
  });

  //! client kill ip:port
  client.client_list([&client](cpp_redis::reply& reply) {
    std::string addr;
    std::stringstream ss(reply.as_string());

    ss >> addr >> addr;

    std::string host = std::string(addr.begin() + addr.find('=') + 1, addr.begin() + addr.find(':'));
    int port         = std::stoi(std::string(addr.begin() + addr.find(':') + 1, addr.end()));

    client.client_kill(host, port, [](cpp_redis::reply& reply) {
      std::cout << reply << std::endl; //! OK
    });

    client.commit();
  });

  client.sync_commit();
  std::this_thread::sleep_for(std::chrono::seconds(1));

  if (!client.is_connected()) {
    client.connect("127.0.0.1", 6379, [](const std::string& host, std::size_t port, cpp_redis::client::connect_state status) {
      if (status == cpp_redis::client::connect_state::dropped) {
        std::cout << "client disconnected from " << host << ":" << port << std::endl;
      }
    });
  }

  //! client kill filter
  client.client_list([&client](cpp_redis::reply& reply) {
    std::string id_str;
    std::stringstream ss(reply.as_string());

    ss >> id_str;

    uint64_t id = std::stoi(std::string(id_str.begin() + id_str.find('=') + 1, id_str.end()));
    client.client_kill(id, false, cpp_redis::client::client_type::normal, [](cpp_redis::reply& reply) {
      std::cout << reply << std::endl; //! 1
    });

    client.commit();
  });

  client.sync_commit();
  std::this_thread::sleep_for(std::chrono::seconds(1));

#ifdef _WIN32
  WSACleanup();
#endif /* _WIN32 */

  return 0;
}

High Availability

// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <[email protected]>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <cpp_redis/cpp_redis>

#include <iostream>

#ifdef _WIN32
#include <Winsock2.h>
#endif /* _WIN32 */

int
main(void) {
#ifdef _WIN32
  //! Windows netword DLL init
  WORD version = MAKEWORD(2, 2);
  WSADATA data;

  if (WSAStartup(version, &data) != 0) {
    std::cerr << "WSAStartup() failure" << std::endl;
    return -1;
  }
#endif /* _WIN32 */

  //! Enable logging
  cpp_redis::active_logger = std::unique_ptr<cpp_redis::logger>(new cpp_redis::logger);

  //! High availablity requires at least 2 io service workers
  cpp_redis::network::set_default_nb_workers(2);

  cpp_redis::client client;

  //! Add your sentinels by IP/Host & Port
  client.add_sentinel("127.0.0.1", 26379);

  //! Call connect with optional timeout
  //! Can put a loop around this until is_connected() returns true.
  client.connect("mymaster", [](const std::string& host, std::size_t port, cpp_redis::client::connect_state status) {
    if (status == cpp_redis::client::connect_state::dropped) {
      std::cout << "client disconnected from " << host << ":" << port << std::endl;
    }
  },
    0, -1, 5000);

  // same as client.send({ "SET", "hello", "42" }, ...)
  client.set("hello", "42", [](cpp_redis::reply& reply) {
    std::cout << "set hello 42: " << reply << std::endl;
    // if (reply.is_string())
    //   do_something_with_string(reply.as_string())
  });

  while (true) {
    // same as client.send({ "DECRBY", "hello", 12 }, ...)
    client.incrby("hello", 12, [](cpp_redis::reply& reply) {
      std::cout << "incrby hello 12: " << reply << std::endl;
      // if (reply.is_integer())
      //   do_something_with_integer(reply.as_integer())
    });

    // same as client.send({ "GET", "hello" }, ...)
    client.get("hello", [](cpp_redis::reply& reply) {
      std::cout << "get hello: " << reply << std::endl;
      // if (reply.is_string())
      //   do_something_with_string(reply.as_string())
    });

    // commands are pipelined and only sent when client.commit() is called
    // client.commit();

    // synchronous commit, no timeout
    client.sync_commit();
    std::cout << std::endl;
    std::this_thread::sleep_for(std::chrono::milliseconds(3000));
  }

#ifdef _WIN32
  WSACleanup();
#endif /* _WIN32 */

  return 0;
}

This example is based on a sentinel using the the following default sentinel configuration file:

# Example sentinel.conf

# *** IMPORTANT ***
#
# By default Sentinel will not be reachable from interfaces different than
# localhost, either use the 'bind' directive to bind to a list of network
# interfaces, or disable protected mode with "protected-mode no" by
# adding it to this configuration file.
#
# Before doing that MAKE SURE the instance is protected from the outside
# world via firewalling or other means.
#
# For example you may use one of the following:
#
# bind 127.0.0.1 192.168.1.1
#
# protected-mode no

# port <sentinel-port>
# The port that this sentinel instance will run on
port 26379

# sentinel announce-ip <ip>
# sentinel announce-port <port>
#
# The above two configuration directives are useful in environments where,
# because of NAT, Sentinel is reachable from outside via a non-local address.
#
# When announce-ip is provided, the Sentinel will claim the specified IP address
# in HELLO messages used to gossip its presence, instead of auto-detecting the
# local address as it usually does.
#
# Similarly when announce-port is provided and is valid and non-zero, Sentinel
# will announce the specified TCP port.
#
# The two options don't need to be used together, if only announce-ip is
# provided, the Sentinel will announce the specified IP and the server port
# as specified by the "port" option. If only announce-port is provided, the
# Sentinel will announce the auto-detected local IP and the specified port.
#
# Example:
#
# sentinel announce-ip 1.2.3.4

# dir <working-directory>
# Every long running process should have a well-defined working directory.
# For Redis Sentinel to chdir to /tmp at startup is the simplest thing
# for the process to don't interfere with administrative tasks such as
# unmounting filesystems.
dir /tmp

# sentinel monitor <master-name> <ip> <redis-port> <quorum>
#
# Tells Sentinel to monitor this master, and to consider it in O_DOWN
# (Objectively Down) state only if at least <quorum> sentinels agree.
#
# Note that whatever is the ODOWN quorum, a Sentinel will require to
# be elected by the majority of the known Sentinels in order to
# start a failover, so no failover can be performed in minority.
#
# Slaves are auto-discovered, so you don't need to specify slaves in
# any way. Sentinel itself will rewrite this configuration file adding
# the slaves using additional configuration options.
# Also note that the configuration file is rewritten when a
# slave is promoted to master.
#
# Note: master name should not include special characters or spaces.
# The valid charset is A-z 0-9 and the three characters ".-_".
sentinel monitor mymaster 127.0.0.1 6379 2

# sentinel auth-pass <master-name> <password>
#
# Set the password to use to authenticate with the master and slaves.
# Useful if there is a password set in the Redis instances to monitor.
#
# Note that the master password is also used for slaves, so it is not
# possible to set a different password in masters and slaves instances
# if you want to be able to monitor these instances with Sentinel.
#
# However you can have Redis instances without the authentication enabled
# mixed with Redis instances requiring the authentication (as long as the
# password set is the same for all the instances requiring the password) as
# the AUTH command will have no effect in Redis instances with authentication
# switched off.
#
# Example:
#
# sentinel auth-pass mymaster MySUPER--secret-0123passw0rd

# sentinel down-after-milliseconds <master-name> <milliseconds>
#
# Number of milliseconds the master (or any attached slave or sentinel) should
# be unreachable (as in, not acceptable reply to PING, continuously, for the
# specified period) in order to consider it in S_DOWN state (Subjectively
# Down).
#
# Default is 30 seconds.
sentinel down-after-milliseconds mymaster 30000

# sentinel parallel-syncs <master-name> <numslaves>
#
# How many slaves we can reconfigure to point to the new slave simultaneously
# during the failover. Use a low number if you use the slaves to serve query
# to avoid that all the slaves will be unreachable at about the same
# time while performing the synchronization with the master.
sentinel parallel-syncs mymaster 1

# sentinel failover-timeout <master-name> <milliseconds>
#
# Specifies the failover timeout in milliseconds. It is used in many ways:
#
# - The time needed to re-start a failover after a previous failover was
#   already tried against the same master by a given Sentinel, is two
#   times the failover timeout.
#
# - The time needed for a slave replicating to a wrong master according
#   to a Sentinel current configuration, to be forced to replicate
#   with the right master, is exactly the failover timeout (counting since
#   the moment a Sentinel detected the misconfiguration).
#
# - The time needed to cancel a failover that is already in progress but
#   did not produced any configuration change (SLAVEOF NO ONE yet not
#   acknowledged by the promoted slave).
#
# - The maximum time a failover in progress waits for all the slaves to be
#   reconfigured as slaves of the new master. However even after this time
#   the slaves will be reconfigured by the Sentinels anyway, but not with
#   the exact parallel-syncs progression as specified.
#
# Default is 3 minutes.
sentinel failover-timeout mymaster 180000

# SCRIPTS EXECUTION
#
# sentinel notification-script and sentinel reconfig-script are used in order
# to configure scripts that are called to notify the system administrator
# or to reconfigure clients after a failover. The scripts are executed
# with the following rules for error handling:
#
# If script exits with "1" the execution is retried later (up to a maximum
# number of times currently set to 10).
#
# If script exits with "2" (or an higher value) the script execution is
# not retried.
#
# If script terminates because it receives a signal the behavior is the same
# as exit code 1.
#
# A script has a maximum running time of 60 seconds. After this limit is
# reached the script is terminated with a SIGKILL and the execution retried.

# NOTIFICATION SCRIPT
#
# sentinel notification-script <master-name> <script-path>
# 
# Call the specified notification script for any sentinel event that is
# generated in the WARNING level (for instance -sdown, -odown, and so forth).
# This script should notify the system administrator via email, SMS, or any
# other messaging system, that there is something wrong with the monitored
# Redis systems.
#
# The script is called with just two arguments: the first is the event type
# and the second the event description.
#
# The script must exist and be executable in order for sentinel to start if
# this option is provided.
#
# Example:
#
# sentinel notification-script mymaster /var/redis/notify.sh

# CLIENTS RECONFIGURATION SCRIPT
#
# sentinel client-reconfig-script <master-name> <script-path>
#
# When the master changed because of a failover a script can be called in
# order to perform application-specific tasks to notify the clients that the
# configuration has changed and the master is at a different address.
# 
# The following arguments are passed to the script:
#
# <master-name> <role> <state> <from-ip> <from-port> <to-ip> <to-port>
#
# <state> is currently always "failover"
# <role> is either "leader" or "observer"
# 
# The arguments from-ip, from-port, to-ip, to-port are used to communicate
# the old address of the master and the new address of the elected slave
# (now a master).
#
# This script should be resistant to multiple invocations.
#
# Example:
#
# sentinel client-reconfig-script mymaster /var/redis/reconfig.sh