session

type Config struct {
	ProviderBlockList     map[peer.ID]bool
	ProviderAllowList     map[peer.ID]bool
	DefaultProviderConfig ProviderConfig
	ProviderConfigs       map[peer.ID]ProviderConfig

	// Random is an optional rng, if nil, math/rand will be used.
	Random Random

	// ConnectTimeAlpha is the alpha value for the exponential moving average
	// of the connect time for a storage provider. The connect time is the time
	// it takes to connect to a storage provider, it is used to determine the
	// prioritisation of storage providers. The value determines the weight of
	// previous connect times, a lower value will give more weight to recent
	// connect times. A value of 0 will only use the most recent connect time.
	ConnectTimeAlpha float64
	// FirstByteTimeAlpha is the alpha value for the exponential moving average
	// of the time to first byte for a storage provider. The time to first byte
	// is the time it takes to receive the first byte of data from a storage
	// provider, it is used to determine the prioritisation of storage
	// providers. The value determines the weight of previous time to first
	// bytes, a lower value will give more weight to recent time to first bytes.
	// A value of 0 will only use the most recent time to first byte.
	FirstByteTimeAlpha float64
	// OverallConnectTimeAlpha is the alpha value for the exponential moving
	// average of the overall connect time. The overall connect time is the
	// average connect time of *all* storage providers, used to normalise the
	// connect time metric.
	OverallConnectTimeAlpha float64
	// OverallFirstByteTimeAlpha is the alpha value for the exponential moving
	// average of the overall time to first byte. The overall time to first byte
	// is the average time to first byte of *all* storage providers, used to
	// normalise the time to first byte metric.
	OverallFirstByteTimeAlpha float64
	// BandwidthAlpha is the alpha value for the exponential moving average of
	// the bandwidth metric for a storage provider. The bandwidth metric is
	// measured in bytes per second. The value of BandwidthAlpha determines the
	// weight of previous bandwidth metrics, a lower value will give more weight
	// to recent bandwidth metrics. A value of 0 will only use the most recent
	// bandwidth metric.
	BandwidthAlpha float64
	// OverallBandwidthAlpha is the alpha value for the exponential moving
	// average of the overall bandwidth metric. The overall bandwidth metric is
	// the average bandwidth of *all* storage providers, used to normalise the
	// bandwidth metric.
	OverallBandwidthAlpha float64
	// SuccessAlpha is the alpha value for the exponential moving average of
	// the success metric for a storage provider. The success metric is the
	// ratio of successful retrievals to total retrievals. The value determines
	// the weight of previous success metrics, a lower value will give more
	// weight to recent success metrics. A value of 0 will only use the most
	// recent success metric.
	SuccessAlpha float64

	// ConnectTimeWeight is the scoring weight applied to the connect time
	// exponential moving average for the candidate at time of scoring. The
	// weight is a multiplier the base value, which should be a normalised
	// score in the range of [0, 1].
	ConnectTimeWeight float64
	// FirstByteTimeWeight is the scoring weight applied to the time to first
	// byte exponential moving average for the candidate at time of scoring. The
	// weight is a multiplier the base value, which should be a normalised
	// score in the range of [0, 1].
	FirstByteTimeWeight float64
	// BandwidthWeight is the scoring weight applied to the bandwidth
	// exponential moving average for the candidate at time of scoring. The
	// weight is a multiplier the base value, which should be a normalised
	// score in the range of [0, 1].
	BandwidthWeight float64
	// SuccessWeight is the scoring weight applied to the success exponential
	// moving average for the candidate at time of scoring. The weight is a
	// multiplier the base value, which should be a normalised score in the
	// range of [0, 1] (where each failure contributes a 0 and each success
	// contributes a 1).
	SuccessWeight float64
}

type ProviderConfig struct {
	MaxConcurrentRetrievals uint
}

type Random interface{ Float64() float64 }

type Session struct {
	State
	// contains filtered or unexported fields
}

type SessionState struct {
	// contains filtered or unexported fields
}

type State interface {
	// GetConcurrency returns the number of retrievals the given storage
	// provider is currently recorded as being involved in.
	GetConcurrency(storageProviderId peer.ID) uint

	// RegisterRetrieval registers a retrieval, returning false if the
	// retrieval for this RetrievalID or this CID already exists, or true if it
	// is new.
	RegisterRetrieval(retrievalId types.RetrievalID, cid cid.Cid, selector datamodel.Node) bool

	// AddToRetrieval adds a set of storage providers to an existing retrieval,
	// this will increase the concurrency for each of the storage providers
	// until the retrieval has finished.
	AddToRetrieval(retrievalId types.RetrievalID, storageProviderIds []peer.ID) error

	// EndRetrieval cleans up an existing retrieval.
	EndRetrieval(retrievalId types.RetrievalID) error

	// RecordConnectTime records the time it took to connect to a storage
	// provider. This is used for prioritisation of storage providers and is
	// recorded with a decay according to SessionStateConfig#ConnectTimeAlpha.
	RecordConnectTime(storageProviderId peer.ID, connectTime time.Duration)

	// RecordFirstByteTime records the time it took to receive the first byte
	// from a storage provider. This is used for prioritisation of storage
	// providers and is recorded with a decay according to
	// SessionStateConfig#FirstByteTimeAlpha.
	RecordFirstByteTime(storageProviderId peer.ID, firstByteTime time.Duration)

	// RecordFailure records a failure for a storage provider. This is used for
	// prioritisation of storage providers and is recorded as a success=0 with a
	// decay according to SessionStateConfig#SuccessAlpha.
	RecordFailure(retrievalId types.RetrievalID, storageProviderId peer.ID) error

	// RecordSuccess records a success for a storage provider. This is used for
	// prioritisation of storage providers and is recorded as a success=1 with a
	// decay according to SessionStateConfig#SuccessAlpha. Bandwidth is also
	// used for prioritisation and is recorded with a decay according to
	// SessionStateConfig#BandwidthAlpha.
	RecordSuccess(storageProviderId peer.ID, bandwidthBytesPerSecond uint64)

	// ChooseNextProvider compares a list of storage providers and returns the
	// index of the next storage provider to use. This uses both historically
	// collected state and information contained within the metadata, depending
	// on protocol.
	ChooseNextProvider(peers []peer.ID, metadata []metadata.Protocol) int
}