84 lines
3 KiB
Go
84 lines
3 KiB
Go
package main
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import (
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"reflect"
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"github.com/pkg/errors"
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)
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// configuration captures the plugin's external configuration as exposed in the Mattermost server
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// configuration, as well as values computed from the configuration. Any public fields will be
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// deserialized from the Mattermost server configuration in OnConfigurationChange.
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//
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// As plugins are inherently concurrent (hooks being called asynchronously), and the plugin
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// configuration can change at any time, access to the configuration must be synchronized. The
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// strategy used in this plugin is to guard a pointer to the configuration, and clone the entire
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// struct whenever it changes. You may replace this with whatever strategy you choose.
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//
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// If you add non-reference types to your configuration struct, be sure to rewrite Clone as a deep
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// copy appropriate for your types.
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type configuration struct {
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}
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// Clone shallow copies the configuration. Your implementation may require a deep copy if
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// your configuration has reference types.
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func (c *configuration) Clone() *configuration {
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var clone = *c
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return &clone
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}
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// getConfiguration retrieves the active configuration under lock, making it safe to use
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// concurrently. The active configuration may change underneath the client of this method, but
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// the struct returned by this API call is considered immutable.
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func (p *Plugin) getConfiguration() *configuration {
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p.configurationLock.RLock()
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defer p.configurationLock.RUnlock()
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if p.configuration == nil {
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return &configuration{}
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}
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return p.configuration
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}
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// setConfiguration replaces the active configuration under lock.
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//
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// Do not call setConfiguration while holding the configurationLock, as sync.Mutex is not
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// reentrant. In particular, avoid using the plugin API entirely, as this may in turn trigger a
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// hook back into the plugin. If that hook attempts to acquire this lock, a deadlock may occur.
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//
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// This method panics if setConfiguration is called with the existing configuration. This almost
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// certainly means that the configuration was modified without being cloned and may result in
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// an unsafe access.
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func (p *Plugin) setConfiguration(configuration *configuration) {
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p.configurationLock.Lock()
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defer p.configurationLock.Unlock()
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if configuration != nil && p.configuration == configuration {
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// Ignore assignment if the configuration struct is empty. Go will optimize the
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// allocation for same to point at the same memory address, breaking the check
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// above.
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if reflect.ValueOf(*configuration).NumField() == 0 {
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return
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}
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panic("setConfiguration called with the existing configuration")
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}
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p.configuration = configuration
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}
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// OnConfigurationChange is invoked when configuration changes may have been made.
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func (p *Plugin) OnConfigurationChange() error {
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var configuration = new(configuration)
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// Load the public configuration fields from the Mattermost server configuration.
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if err := p.API.LoadPluginConfiguration(configuration); err != nil {
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return errors.Wrap(err, "failed to load plugin configuration")
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}
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p.setConfiguration(configuration)
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return nil
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}
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