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e7bd392a69
This fixes an important bug with listing that affects users with more than 500 objects in a listing operation.
70 lines
2.2 KiB
Go
70 lines
2.2 KiB
Go
// Copyright (C) 2019 Storj Labs, Inc.
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// See LICENSE for copying information.
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package storj
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// RedundancyScheme specifies the parameters and the algorithm for redundancy.
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type RedundancyScheme struct {
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// Algorithm determines the algorithm to be used for redundancy.
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Algorithm RedundancyAlgorithm
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// ShareSize is the size in bytes for each erasure shares.
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ShareSize int32
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// RequiredShares is the minimum number of shares required to recover a
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// stripe, reed-solomon k.
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RequiredShares int16
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// RepairShares is the minimum number of safe shares that can remain
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// before a repair is triggered.
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RepairShares int16
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// OptimalShares is the desired total number of shares for a segment.
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OptimalShares int16
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// TotalShares is the number of shares to encode. If it is larger than
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// OptimalShares, slower uploads of the excess shares will be aborted in
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// order to improve performance.
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TotalShares int16
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}
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// IsZero returns true if no field in the struct is set to non-zero value.
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func (scheme RedundancyScheme) IsZero() bool {
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return scheme == (RedundancyScheme{})
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}
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// StripeSize is the number of bytes for a stripe.
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// Stripes are erasure encoded and split into n shares, where we need k to
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// reconstruct the stripe. Therefore a stripe size is the erasure share size
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// times the required shares, k.
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func (scheme RedundancyScheme) StripeSize() int32 {
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return scheme.ShareSize * int32(scheme.RequiredShares)
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}
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// DownloadNodes calculates the number of nodes needed to download in the
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// presence of node failure based on t = k + (n-o)k/o.
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func (scheme RedundancyScheme) DownloadNodes() int32 {
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extra := int32(1)
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if scheme.OptimalShares > 0 {
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extra = int32(((scheme.TotalShares - scheme.OptimalShares) * scheme.RequiredShares) / scheme.OptimalShares)
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if extra == 0 {
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// ensure there is at least one extra node, so we can have error detection/correction
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extra = 1
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}
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}
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needed := int32(scheme.RequiredShares) + extra
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if needed > int32(scheme.TotalShares) {
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needed = int32(scheme.TotalShares)
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}
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return needed
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}
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// RedundancyAlgorithm is the algorithm used for redundancy.
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type RedundancyAlgorithm byte
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// List of supported redundancy algorithms.
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const (
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InvalidRedundancyAlgorithm = RedundancyAlgorithm(iota)
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ReedSolomon
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)
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