github.com/annchain/OG@v0.0.9/metrics/healthcheck.go (about)

     1  package metrics
     2  
     3  // Healthchecks hold an error value describing an arbitrary up/down status.
     4  type Healthcheck interface {
     5  	Check()
     6  	Error() error
     7  	Healthy()
     8  	Unhealthy(error)
     9  }
    10  
    11  // NewHealthcheck constructs a new Healthcheck which will use the given
    12  // function to update its status.
    13  func NewHealthcheck(f func(Healthcheck)) Healthcheck {
    14  	if !Enabled {
    15  		return NilHealthcheck{}
    16  	}
    17  	return &StandardHealthcheck{nil, f}
    18  }
    19  
    20  // NilHealthcheck is a no-op.
    21  type NilHealthcheck struct{}
    22  
    23  // Check is a no-op.
    24  func (NilHealthcheck) Check() {}
    25  
    26  // Error is a no-op.
    27  func (NilHealthcheck) Error() error { return nil }
    28  
    29  // Healthy is a no-op.
    30  func (NilHealthcheck) Healthy() {}
    31  
    32  // Unhealthy is a no-op.
    33  func (NilHealthcheck) Unhealthy(error) {}
    34  
    35  // StandardHealthcheck is the standard implementation of a Healthcheck and
    36  // stores the status and a function to call to update the status.
    37  type StandardHealthcheck struct {
    38  	err error
    39  	f   func(Healthcheck)
    40  }
    41  
    42  // Check runs the healthcheck function to update the healthcheck's status.
    43  func (h *StandardHealthcheck) Check() {
    44  	h.f(h)
    45  }
    46  
    47  // Error returns the healthcheck's status, which will be nil if it is healthy.
    48  func (h *StandardHealthcheck) Error() error {
    49  	return h.err
    50  }
    51  
    52  // Healthy marks the healthcheck as healthy.
    53  func (h *StandardHealthcheck) Healthy() {
    54  	h.err = nil
    55  }
    56  
    57  // Unhealthy marks the healthcheck as unhealthy.  The error is stored and
    58  // may be retrieved by the Error method.
    59  func (h *StandardHealthcheck) Unhealthy(err error) {
    60  	h.err = err
    61  }