[#node-KernelNotifications]
= xref:node.adoc[node]::KernelNotifications
:relfileprefix: ../
:mrdocs:

Kernel notification handler that tracks chain state for code above the validation layer.

== Synopsis

Declared in `<node/kernel_notifications.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class KernelNotifications
    : public xref:kernel/Notifications.adoc[kernel::Notifications]
----

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:kernel/Notifications.adoc[kernel::Notifications]`
| A base class defining functions for notifying about certain kernel events.
|===

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:node/KernelNotifications/2constructor.adoc[`KernelNotifications`]         [.small]#[constructor]#
| Construct the notification handler.
| xref:node/KernelNotifications/TipBlock.adoc[`TipBlock`] 
| The block for which the last blockTip notification was received. It's first set when the tip is connected during node initialization. Might be unset during an early shutdown.
| xref:node/KernelNotifications/blockTip.adoc[`blockTip`]  [.small]#[virtual]#
| Handle a new chain tip being connected.
| xref:node/KernelNotifications/fatalError.adoc[`fatalError`]  [.small]#[virtual]#
| Handle a fatal, unrecoverable error, requesting shutdown unless disabled.
| xref:node/KernelNotifications/flushError.adoc[`flushError`]  [.small]#[virtual]#
| Handle a non‐fatal error while flushing state to disk.
| xref:node/KernelNotifications/headerTip.adoc[`headerTip`]  [.small]#[virtual]#
| Handle the best header advancing during headers synchronization.
| xref:node/KernelNotifications/progress.adoc[`progress`]  [.small]#[virtual]#
| Report progress of a long‐running operation to the UI.
| xref:node/KernelNotifications/setChainstateLoaded.adoc[`setChainstateLoaded`] 
| Record whether the chainstate has finished loading.
| xref:node/KernelNotifications/warningSet-0e.adoc[`warningSet`] 
| `warningSet` overloads
| xref:node/KernelNotifications/warningUnset-04.adoc[`warningUnset`] 
| `warningUnset` overloads
|===


== Data Members

[cols="1,4"]
|===
| Name| Description
| xref:node/KernelNotifications/m_shutdown_on_fatal_error.adoc[`m_shutdown_on_fatal_error`] 
| Useful for tests, can be set to false to avoid shutdown on fatal error.
| xref:node/KernelNotifications/m_state.adoc[`m_state`] 
| Kernel state guarded by m_tip_block_mutex.
| xref:node/KernelNotifications/m_stop_at_height.adoc[`m_stop_at_height`] 
| Block height after which blockTip notification will return Interrupted{}, if >0.
| xref:node/KernelNotifications/m_tip_block_cv.adoc[`m_tip_block_cv`] 
| Signaled when the tip‐block state changes.
| xref:node/KernelNotifications/m_tip_block_mutex.adoc[`m_tip_block_mutex`] 
| Guards the tip‐block state and its condition variable.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:node/InterruptWait.adoc[`InterruptWait`]
| Interrupt a blocking wait call.
| xref:FatalError.adoc[`::FatalError`]
| Report an unrecoverable error, flag the validation state as failed, and notify the node to shut down.
|===


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