Documentation
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Overview ¶
Package preference contains routines for maintaining order of preference for expensive processes such as RPC methods.
Index ¶
Constants ¶
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Functions ¶
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Types ¶
type Preference ¶
type Preference struct {
// contains filtered or unexported fields
}
Preference instances maintain the order of preference for RPC methods to complete an API call. Although this documentation assumes the client is managing RPC methods, a Preference instance may be used to maintain order of preference for completing any expensive process.
Clients store RPC methods in a slice by order of preference. The best method is stored in [0]; the next best in [1] etc. A preference instance tells the client what order to try RPC methods according to their index in that slice. If there are 4 RPC methods, the Indexes() method will return {0, 1, 2, 3} which means try the most preferred method first; the next preferred second and so forth. Generally, the client will have success with the most preferred method, but when that method fails, the client can tell the instance what method was successful.
When the client finds a successful method, the client calls SetFirstIndex to tell the instance what method was successful. If client calls SetFirstIndex(2), Index() will return {2, 0, 1, 3} which means try the method at index 2 first since that one brought success, then try the most preferred method then the next preferred method and finally the least preferred method. Sometimes it may be desirable to try the most preferred method first eventually.
For that reason, a Preference instance may be set up so that after SetFirstIndex() is called n consecutive times with the same index, the first index to try is reset to 0 to ensure that eventually the most preferred RPC method is tried first once again.
func New ¶
func New(count int, consecutiveCallsForReset int) *Preference
New creates a brand new Preference instance. count is the number of RPC methods to try. consecutiveCallsForReset is how many consecutive times SetFirstIndex() must be called with the same index to reset the first index to 0. consecutiveCallsForReset <= 0 means never reset.
New panics if count <= 0.
func (*Preference) FirstIndex ¶
func (p *Preference) FirstIndex() int
FirstIndex returns the index of the first RPC method to try
func (*Preference) Indexes ¶
func (p *Preference) Indexes() []int
Indexes returns the order to try RPC methods by index
func (*Preference) SetFirstIndex ¶
func (p *Preference) SetFirstIndex(index int)
SetFirstIndex tells this instance the index of the RPC method that succeeded.
SetFirstIndex panics if index < 0 or index >= count.
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