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Diffstat (limited to 'swarm/storage/feed/lookup/epoch.go')
-rw-r--r-- | swarm/storage/feed/lookup/epoch.go | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/swarm/storage/feed/lookup/epoch.go b/swarm/storage/feed/lookup/epoch.go new file mode 100644 index 000000000..bafe95477 --- /dev/null +++ b/swarm/storage/feed/lookup/epoch.go @@ -0,0 +1,91 @@ +// Copyright 2018 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. + +package lookup + +import ( + "encoding/binary" + "errors" + "fmt" +) + +// Epoch represents a time slot at a particular frequency level +type Epoch struct { + Time uint64 `json:"time"` // Time stores the time at which the update or lookup takes place + Level uint8 `json:"level"` // Level indicates the frequency level as the exponent of a power of 2 +} + +// EpochID is a unique identifier for an Epoch, based on its level and base time. +type EpochID [8]byte + +// EpochLength stores the serialized binary length of an Epoch +const EpochLength = 8 + +// MaxTime contains the highest possible time value an Epoch can handle +const MaxTime uint64 = (1 << 56) - 1 + +// Base returns the base time of the Epoch +func (e *Epoch) Base() uint64 { + return getBaseTime(e.Time, e.Level) +} + +// ID Returns the unique identifier of this epoch +func (e *Epoch) ID() EpochID { + base := e.Base() + var id EpochID + binary.LittleEndian.PutUint64(id[:], base) + id[7] = e.Level + return id +} + +// MarshalBinary implements the encoding.BinaryMarshaller interface +func (e *Epoch) MarshalBinary() (data []byte, err error) { + b := make([]byte, 8) + binary.LittleEndian.PutUint64(b[:], e.Time) + b[7] = e.Level + return b, nil +} + +// UnmarshalBinary implements the encoding.BinaryUnmarshaller interface +func (e *Epoch) UnmarshalBinary(data []byte) error { + if len(data) != EpochLength { + return errors.New("Invalid data unmarshalling Epoch") + } + b := make([]byte, 8) + copy(b, data) + e.Level = b[7] + b[7] = 0 + e.Time = binary.LittleEndian.Uint64(b) + return nil +} + +// After returns true if this epoch occurs later or exactly at the other epoch. +func (e *Epoch) After(epoch Epoch) bool { + if e.Time == epoch.Time { + return e.Level < epoch.Level + } + return e.Time >= epoch.Time +} + +// Equals compares two epochs and returns true if they refer to the same time period. +func (e *Epoch) Equals(epoch Epoch) bool { + return e.Level == epoch.Level && e.Base() == epoch.Base() +} + +// String implements the Stringer interface. +func (e *Epoch) String() string { + return fmt.Sprintf("Epoch{Time:%d, Level:%d}", e.Time, e.Level) +} |