tqlcommon

Common Functions

The following functions can be used in any implementation of the Telemetry Query Language. Although they are tested using pdata for convenience, the function implementation only interact with native Go types or types defined in the tql package.

Factory Functions

• Join
• IsMatch
• Int

Functions

• set
• replace_match
• replace_pattern

Concat

Concat(delimiter, ...values)

The Concat factory function takes a delimiter and a sequence of values and concatenates their string representation. Unsupported values, such as lists or maps that may substantially increase payload size, are not added to the resulting string.

delimiter is a string value that is placed between strings during concatenation. If no delimiter is desired, then simply pass an empty string.

values is a series of values passed as arguments. It supports paths, primitive values, and byte slices (such as trace IDs or span IDs).

Examples:

• Concat(": ", attributes["http.method"], attributes["http.path"])

• Concat(" ", name, 1)

• Concat("", "HTTP method is: ", attributes["http.method"])

IsMatch

IsMatch(target, pattern)

The IsMatch factory function returns true if the target matches the regex pattern.

target is either a path expression to a telemetry field to retrieve or a literal string. pattern is a regexp pattern.

The function matches the target against the pattern, returning true if the match is successful and false otherwise. If target is nil or not a string false is always returned.

Examples:

• IsMatch(attributes["http.path"], "foo")

• IsMatch("string", ".*ring")

Int

Int(value)

The Int factory function converts the value to int type.

The returned type is int64.

The input value types:

• float64. Fraction is discharged (truncation towards zero).
• string. Trying to parse an integer from string if it fails then nil will be returned.
• bool. If value is true, then the function will return 1 otherwise 0.
• int64. The function returns the value without changes.

If value is another type or parsing failed nil is always returned.

The value is either a path expression to a telemetry field to retrieve or a literal.

Examples:

• Int(attributes["http.status_code"])

• Int("2.0")

set

set(target, value)

The set function allows users to set a telemetry field using a value.

target is a path expression to a telemetry field. value is any value type. If value resolves to nil, e.g. it references an unset map value, there will be no action.

How the underlying telemetry field is updated is decided by the path expression implementation provided by the user to the tql.ParseQueries.

Examples:

• set(attributes["http.path"], "/foo")

• set(name, attributes["http.route"])

• set(trace_state["svc"], "example")

• set(attributes["source"], trace_state["source"])

replace_match

replace_match(target, pattern, replacement)

The replace_match function allows replacing entire strings if they match a glob pattern.

target is a path expression to a telemetry field. pattern is a string following filepath.Match syntax. replacement is a string.

If target matches pattern it will get replaced with replacement.

Examples:

• replace_match(attributes["http.target"], "/user/*/list/*", "/user/{userId}/list/{listId}")

replace_pattern

replace_pattern(target, regex, replacement)

The replace_pattern function allows replacing all string sections that match a regex pattern with a new value.

target is a path expression to a telemetry field. regex is a regex string indicating a segment to replace. replacement is a string.

If one or more sections of target match regex they will get replaced with replacement.

Examples:

• replace_pattern(resource.attributes["process.command_line"], "password\\=[^\\s]*(\\s?)", "password=***")