mirror of https://github.com/lightninglabs/loop
liquidity: add manager with updatable parameters
parent
2ac5d8defa
commit
ce10cc7959
@ -0,0 +1,133 @@
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// Package liquidity is responsible for monitoring our node's liquidity. It
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// allows setting of a liquidity rule which describes the desired liquidity
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// balance on a per-channel basis.
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package liquidity
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import (
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"context"
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"fmt"
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"strings"
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"sync"
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"github.com/lightningnetwork/lnd/lnwire"
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)
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var (
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// ErrZeroChannelID is returned if we get a rule for a 0 channel ID.
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ErrZeroChannelID = fmt.Errorf("zero channel ID not allowed")
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)
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// Config contains the external functionality required to run the
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// liquidity manager.
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type Config struct {
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// LoopOutRestrictions returns the restrictions that the server applies
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// to loop out swaps.
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LoopOutRestrictions func(ctx context.Context) (*Restrictions, error)
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}
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// Parameters is a set of parameters provided by the user which guide
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// how we assess liquidity.
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type Parameters struct {
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// ChannelRules maps a short channel ID to a rule that describes how we
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// would like liquidity to be managed.
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ChannelRules map[lnwire.ShortChannelID]*ThresholdRule
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}
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// newParameters creates an empty set of parameters.
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func newParameters() Parameters {
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return Parameters{
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ChannelRules: make(map[lnwire.ShortChannelID]*ThresholdRule),
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}
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}
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// String returns the string representation of our parameters.
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func (p Parameters) String() string {
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channelRules := make([]string, 0, len(p.ChannelRules))
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for channel, rule := range p.ChannelRules {
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channelRules = append(
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channelRules, fmt.Sprintf("%v: %v", channel, rule),
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)
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}
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return fmt.Sprintf("channel rules: %v",
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strings.Join(channelRules, ","))
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}
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// validate checks whether a set of parameters is valid.
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func (p Parameters) validate() error {
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for channel, rule := range p.ChannelRules {
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if channel.ToUint64() == 0 {
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return ErrZeroChannelID
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}
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if err := rule.validate(); err != nil {
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return fmt.Errorf("channel: %v has invalid rule: %v",
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channel.ToUint64(), err)
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}
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}
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return nil
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}
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// Manager contains a set of desired liquidity rules for our channel
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// balances.
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type Manager struct {
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// cfg contains the external functionality we require to determine our
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// current liquidity balance.
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cfg *Config
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// params is the set of parameters we are currently using. These may be
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// updated at runtime.
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params Parameters
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// paramsLock is a lock for our current set of parameters.
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paramsLock sync.Mutex
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}
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// NewManager creates a liquidity manager which has no rules set.
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func NewManager(cfg *Config) *Manager {
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return &Manager{
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cfg: cfg,
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params: newParameters(),
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}
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}
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// GetParameters returns a copy of our current parameters.
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func (m *Manager) GetParameters() Parameters {
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m.paramsLock.Lock()
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defer m.paramsLock.Unlock()
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return cloneParameters(m.params)
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}
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// SetParameters updates our current set of parameters if the new parameters
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// provided are valid.
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func (m *Manager) SetParameters(params Parameters) error {
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if err := params.validate(); err != nil {
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return err
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}
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m.paramsLock.Lock()
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defer m.paramsLock.Unlock()
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m.params = cloneParameters(params)
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return nil
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}
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// cloneParameters creates a deep clone of a parameters struct so that callers
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// cannot mutate our parameters. Although our parameters struct itself is not
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// a reference, we still need to clone the contents of maps.
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func cloneParameters(params Parameters) Parameters {
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paramCopy := Parameters{
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ChannelRules: make(map[lnwire.ShortChannelID]*ThresholdRule,
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len(params.ChannelRules)),
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}
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for channel, rule := range params.ChannelRules {
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ruleCopy := *rule
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paramCopy.ChannelRules[channel] = &ruleCopy
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}
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return paramCopy
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}
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@ -0,0 +1,66 @@
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package liquidity
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import (
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"context"
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"testing"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/stretchr/testify/require"
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)
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// newTestConfig creates a default test config.
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func newTestConfig() *Config {
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return &Config{
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LoopOutRestrictions: func(_ context.Context) (*Restrictions,
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error) {
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return NewRestrictions(1, 10000), nil
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},
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}
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}
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// TestParameters tests getting and setting of parameters for our manager.
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func TestParameters(t *testing.T) {
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manager := NewManager(newTestConfig())
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chanID := lnwire.NewShortChanIDFromInt(1)
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// Start with the case where we have no rules set.
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startParams := manager.GetParameters()
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require.Equal(t, newParameters(), startParams)
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// Mutate the parameters returned by our get function.
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startParams.ChannelRules[chanID] = NewThresholdRule(1, 1)
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// Make sure that we have not mutated the liquidity manager's params
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// by making this change.
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params := manager.GetParameters()
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require.Equal(t, newParameters(), params)
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// Provide a valid set of parameters and validate assert that they are
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// set.
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originalRule := NewThresholdRule(10, 10)
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expected := Parameters{
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ChannelRules: map[lnwire.ShortChannelID]*ThresholdRule{
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chanID: originalRule,
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},
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}
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err := manager.SetParameters(expected)
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require.NoError(t, err)
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// Check that changing the parameters we just set does not mutate
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// our liquidity manager's parameters.
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expected.ChannelRules[chanID] = NewThresholdRule(11, 11)
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params = manager.GetParameters()
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require.NoError(t, err)
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require.Equal(t, originalRule, params.ChannelRules[chanID])
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// Set invalid parameters and assert that we fail.
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expected.ChannelRules = map[lnwire.ShortChannelID]*ThresholdRule{
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lnwire.NewShortChanIDFromInt(0): NewThresholdRule(1, 2),
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}
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err = manager.SetParameters(expected)
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require.Equal(t, ErrZeroChannelID, err)
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}
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package liquidity
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import (
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"fmt"
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"github.com/btcsuite/btcutil"
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)
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// Restrictions indicates the restrictions placed on a swap.
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type Restrictions struct {
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// Minimum is the minimum amount we can swap, inclusive.
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Minimum btcutil.Amount
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// Maximum is the maximum amount we can swap, inclusive.
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Maximum btcutil.Amount
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}
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// String returns a string representation of a set of restrictions.
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func (r *Restrictions) String() string {
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return fmt.Sprintf("%v-%v", r.Minimum, r.Maximum)
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}
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// NewRestrictions creates a set of restrictions.
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func NewRestrictions(minimum, maximum btcutil.Amount) *Restrictions {
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return &Restrictions{
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Minimum: minimum,
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Maximum: maximum,
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}
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}
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package liquidity
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import (
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"errors"
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"fmt"
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)
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var (
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// errInvalidLiquidityThreshold is returned when a liquidity threshold
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// has an invalid value.
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errInvalidLiquidityThreshold = errors.New("liquidity threshold must " +
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"be in [0:100)")
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// errInvalidThresholdSum is returned when the sum of the percentages
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// provided for a threshold rule is >= 100.
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errInvalidThresholdSum = errors.New("sum of incoming and outgoing " +
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"percentages must be < 100")
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)
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// ThresholdRule is a liquidity rule that implements minimum incoming and
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// outgoing liquidity threshold.
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type ThresholdRule struct {
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// MinimumIncoming is the percentage of incoming liquidity that we do
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// not want to drop below.
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MinimumIncoming int
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// MinimumOutgoing is the percentage of outgoing liquidity that we do
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// not want to drop below.
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MinimumOutgoing int
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}
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// NewThresholdRule returns a new threshold rule.
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func NewThresholdRule(minIncoming, minOutgoing int) *ThresholdRule {
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return &ThresholdRule{
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MinimumIncoming: minIncoming,
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MinimumOutgoing: minOutgoing,
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}
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}
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// String returns a string representation of a rule.
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func (r *ThresholdRule) String() string {
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return fmt.Sprintf("threshold rule: minimum incoming: %v%%, minimum "+
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"outgoing: %v%%", r.MinimumIncoming, r.MinimumOutgoing)
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}
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// validate validates the parameters that a rule was created with.
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func (r *ThresholdRule) validate() error {
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if r.MinimumIncoming < 0 || r.MinimumIncoming > 100 {
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return errInvalidLiquidityThreshold
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}
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if r.MinimumOutgoing < 0 || r.MinimumOutgoing > 100 {
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return errInvalidLiquidityThreshold
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}
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if r.MinimumIncoming+r.MinimumOutgoing >= 100 {
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return errInvalidThresholdSum
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}
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return nil
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}
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package liquidity
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import (
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"testing"
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"github.com/stretchr/testify/require"
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)
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// TestValidateThreshold tests validation of the values set for a threshold
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// rule.
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func TestValidateThreshold(t *testing.T) {
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tests := []struct {
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name string
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threshold ThresholdRule
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err error
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}{
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{
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name: "values ok",
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threshold: ThresholdRule{
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MinimumIncoming: 20,
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MinimumOutgoing: 20,
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},
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err: nil,
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},
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{
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name: "negative incoming",
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threshold: ThresholdRule{
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MinimumIncoming: -1,
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MinimumOutgoing: 20,
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},
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err: errInvalidLiquidityThreshold,
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},
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{
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name: "negative outgoing",
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threshold: ThresholdRule{
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MinimumIncoming: 20,
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MinimumOutgoing: -1,
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},
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err: errInvalidLiquidityThreshold,
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},
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{
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name: "incoming > 1",
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threshold: ThresholdRule{
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MinimumIncoming: 120,
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MinimumOutgoing: 20,
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},
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err: errInvalidLiquidityThreshold,
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},
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{
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name: "outgoing >1",
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threshold: ThresholdRule{
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MinimumIncoming: 20,
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MinimumOutgoing: 120,
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},
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err: errInvalidLiquidityThreshold,
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},
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{
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name: "sum < 100",
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threshold: ThresholdRule{
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MinimumIncoming: 60,
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MinimumOutgoing: 39,
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},
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err: nil,
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},
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{
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name: "sum = 100",
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threshold: ThresholdRule{
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MinimumIncoming: 60,
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MinimumOutgoing: 40,
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},
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err: errInvalidThresholdSum,
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},
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{
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name: "sum > 100",
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threshold: ThresholdRule{
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MinimumIncoming: 60,
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MinimumOutgoing: 60,
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},
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err: errInvalidThresholdSum,
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},
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}
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for _, testCase := range tests {
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testCase := testCase
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t.Run(testCase.name, func(t *testing.T) {
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t.Parallel()
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err := testCase.threshold.validate()
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require.Equal(t, testCase.err, err)
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})
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}
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}
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