SYNOPSIS

#include <corosync/sam.h>

cs_error_t sam_initialize (int time_interval, sam_recovery_policy_t recovery_policy);

DESCRIPTION

The sam_initialize function is used to initialize health checking of a process.

Application can have only one instance of SAM. This function must be called before any other of SAM functions. It is recommended to initialize before the process begins any process initialization.

The time_interval parameter is a timeout in milliseconds before taking recovery action after having not received a healthcheck.

If time_interval parameter is zero, there is no time limit and no healthcheck must be sent by the process. In this operational mode, a process failure will continue to execute the recovery policy.

The recovery_policy is defined as type:

  typedef enum {
        SAM_RECOVERY_POLICY_QUIT = 1,
        SAM_RECOVERY_POLICY_RESTART = 2,
        SAM_RECOVERY_POLICY_QUORUM = 0x08,
        SAM_RECOVERY_POLICY_QUORUM_QUIT = SAM_RECOVERY_POLICY_QUORUM | SAM_RECOVERY_POLICY_QUIT,
        SAM_RECOVERY_POLICY_QUORUM_RESTART = SAM_RECOVERY_POLICY_QUORUM | SAM_RECOVERY_POLICY_RESTART,
        SAM_RECOVERY_POLICY_CMAP = 0x10,
        SAM_RECOVERY_POLICY_CONFDB = 0x10,
  } sam_recovery_policy_t;

where

SAM_RECOVERY_POLICY_QUIT

on failure, the process will terminate.

SAM_RECOVERY_POLICY_RESTART

on failure, the process will restart.

SAM_RECOVERY_POLICY_QUORUM

is not policy. Used only as flag meaning quorum integration

SAM_RECOVERY_POLICY_QUORUM_QUIT

same as SAM_RECOVERY_POLICY_QUIT but sam_start (3) will block until corosync becomes quorate and process will be terminated if quorum is lost.

SAM_RECOVERY_POLICY_QUORUM_RESTART

same as SAM_RECOVERY_POLICY_RESTART but sam_start (3) will block until corosync becomes quorate and process will be restarted if quorum is lost.

SAM_RECOVERY_POLICY_CMAP

is not policy. Used only as flag meaning cmap integration. It can be used with all previous policies. For backward compatibility, SAM_RECOVERY_POLICY_CONFDB with same meaning as SAM_RECOVERY_POLICY_CMAP is also provided.

To perform event driven healthchecking, sam_register(3) and sam_start(3) functions must called. Event driven healthchecking causes the duplicate standby process running the SAM serve rto periodically request healthchecks from the active process.

RETURN VALUE

This call return CS_OK value if successful, otherwise and error is returned.