Enum SiblingMergeBehavior

#[repr(i32)]
pub enum SiblingMergeBehavior {
    Unspecified = 0,
    ByTrackName = 1,
    None = 2,
    BySiblingMergeKey = 3,
}

Specifies how the analysis tools should “merge” different sibling TrackEvent tracks.

For two or more tracks to be merged, they must be “eligible” siblings. Eligibility is determined by the following rules:

1. All tracks must have the same parent.
2. All tracks must have the same sibling_merge_behavior. The only exception is SIBLING_MERGE_BEHAVIOR_UNSPECIFIED which is treated as SIBLING_MERGE_BEHAVIOR_BY_TRACK_NAME.
3. Depending on the behavior, the corresponding key must match (e.g. name for BY_TRACK_NAME, sibling_merge_key for BY_SIBLING_MERGE_KEY).

Specifically:

• in the UI, all tracks which are merged together will be displayed as a single “visual” track.
• in the trace processor, all tracks which are merged together will be “multiplexed” into n “analysis” tracks where n is the maximum number of tracks which have an active event at the same time.

When tracks are merged togther, the properties for the merged track will be chosen from the source tracks based on the following rules:

• for sibling_order_rank: the rank of the merged track will be the smallest rank among the source tracks.
• for all other properties: the property taken is unspecified and can be any value provided by one of the source tracks. This can lead to non-deterministic behavior.
  • examples of other properties include name, child_ordering etc.
  • because of this, it’s strongly recommended to ensure that all source tracks have the same value for these properties.
  • the trace processor will also emit an error stat if it detects that the properties are not the same across all source tracks.

Note: merging is done recursively so entire trees of tracks can be merged together. To make this clearer, consider an example track hierarchy (in the diagrams: “smk” refers to “sibling_merge_key”, the first word on a track line, like “Updater”, is its ‘name’ property):

Initial track hierarchy: SystemActivity ├── AuthService (smk: “auth_main_cluster”) │ └── LoginOp (smk: “login_v1”) ├── AuthService (smk: “auth_main_cluster”) │ └── LoginOp (smk: “login_v1”) ├── AuthService (smk: “auth_backup_cluster”) │ └── GuestOp (smk: “guest_v1”) └── UserProfileService (smk: “profile_cluster”) └── GetProfileOp (smk: “getprofile_v1”)

Merging outcomes:

Scenario 1: Merging by SIBLING_MERGE_BEHAVIOR_BY_SIBLING_MERGE_KEY

• The first two “AuthService” tracks merge because they share smk: "auth_main_cluster". Their names are consistent (“AuthService”), aligning with recommendations. The merged track is named “AuthService”.
• The third “AuthService” track (with smk: "auth_backup_cluster") remains separate, as its sibling_merge_key is different.
• “UserProfileService” also remains separate.
• Within the merged “AuthService” (from “auth_main_cluster”): “LoginOp” get merged as they have the same sibling merge key.

Resulting UI (when merging by SIBLING_MERGE_KEY): SystemActivity ├── AuthService (merged by smk: “auth_main_cluster”) │ ├── LoginOp (merged by smk: “login_v1”) ├── AuthService (smk: “auth_backup_cluster”) │ └── GuestOp (smk: “guest_v1”) └── UserProfileService (smk: “profile_cluster”) └── GetProfileOp (smk: “getprofile_v1”)

Scenario 2: Merging by SIBLING_MERGE_BEHAVIOR_BY_TRACK_NAME

• All three tracks named “AuthService” merge because they share the same name. The merged track is named “AuthService”. The sibling_merge_key for this merged track would be taken from one of the source tracks (e.g., “auth_main_cluster” or “auth_backup_cluster”), which could be relevant if its children had key-based merge behaviors.
• “UserProfileService” remains separate due to its different name.
• Within the single merged “AuthService” track: “LoginOp”, “GuestOp” become siblings. “LoginOp” tracks gets merged as they have the same name.

Resulting UI (when merging by SIBLING_MERGE_BEHAVIOR_BY_TRACK_NAME): SystemActivity ├── AuthService (merged from 3 “AuthService” tracks) │ ├── LoginOp (smk: “login_v1”) │ └── GuestOp (smk: “guest_v1”) └── UserProfileService (smk: “profile_cluster”) └── GetProfileOp (smk: “getprofile_v1”)

Note: for tracks where thread or process are set, this option is ignored. See parent_uuid for details.

Variants

Unspecified = 0

When unspecified or not set, defaults to SIBLING_MERGE_BEHAVIOR_BY_TRACK_NAME.

ByTrackName = 1

Merge this track with eligible siblings which have the same name.

This is the default behavior.option.

Fun fact: this is the default beahavior for legacy reasons as the UI has worked this way for years and inherited this behavior from chrome://tracing which has worked this way for even longer

None = 2

Never merge this track with any siblings. Useful if if this track has a specific meaning and you want to see separately from any others.

BySiblingMergeKey = 3

Merge this track with eligible siblings which have the same sibling_merge_key.

Implementations

impl SiblingMergeBehavior

pub fn is_valid(value: i32) -> bool

Returns true if value is a variant of SiblingMergeBehavior.

pub fn from_i32(value: i32) -> Option<SiblingMergeBehavior>

Converts an i32 to a SiblingMergeBehavior, or None if value is not a valid variant.

impl SiblingMergeBehavior

pub fn as_str_name(&self) -> &'static str

String value of the enum field names used in the ProtoBuf definition.

The values are not transformed in any way and thus are considered stable (if the ProtoBuf definition does not change) and safe for programmatic use.

Trait Implementations

impl Clone for SiblingMergeBehavior

fn clone(&self) -> SiblingMergeBehavior

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SiblingMergeBehavior

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SiblingMergeBehavior

fn default() -> SiblingMergeBehavior

Returns the “default value” for a type.

impl From<SiblingMergeBehavior> for i32

fn from(value: SiblingMergeBehavior) -> i32

Converts to this type from the input type.

impl Hash for SiblingMergeBehavior

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for SiblingMergeBehavior

fn cmp(&self, other: &SiblingMergeBehavior) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for SiblingMergeBehavior

fn eq(&self, other: &SiblingMergeBehavior) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for SiblingMergeBehavior

fn partial_cmp(&self, other: &SiblingMergeBehavior) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for SiblingMergeBehavior

impl Eq for SiblingMergeBehavior

impl StructuralPartialEq for SiblingMergeBehavior