X-Git-Url: http://git.efficios.com/?p=ctf.git;a=blobdiff_plain;f=common-trace-format-proposal.txt;h=44092732992146fe4cba31edc131ff5980f3a108;hp=4cb69429e9c0256ee8d46d261e34f924fe747ce4;hb=f42082879eda3db3ce5b5438a06851a37213ce0f;hpb=457d8b0a0cff67a7489b7eead5b8b26701b430f8 diff --git a/common-trace-format-proposal.txt b/common-trace-format-proposal.txt index 4cb6942..4409273 100644 --- a/common-trace-format-proposal.txt +++ b/common-trace-format-proposal.txt @@ -68,14 +68,10 @@ A metadata event stream contains information on trace event types. It describes: 3. Event stream An event stream is divided in contiguous event packets of variable size. These -subdivisions have a variable size. An event packet can contain a certain amount -of padding at the end. The rationale for the event stream design choices is -explained in Appendix B. Stream Header Rationale. - -An event stream is divided in contiguous event packets of variable size. These -subdivisions have a variable size. An event packet can contain a certain amount -of padding at the end. The stream header is repeated at the beginning of each -event packet. +subdivisions have a variable size. An event packet can contain a certain +amount of padding at the end. The stream header is repeated at the +beginning of each event packet. The rationale for the event stream +design choices is explained in Appendix B. Stream Header Rationale. The event stream header will therefore be referred to as the "event packet header" throughout the rest of this document. @@ -103,15 +99,16 @@ types, but must be derived into a type to be usable in an event field. We define "byte-packed" types as aligned on the byte size, namely 8-bit. We define "bit-packed" types as following on the next bit, as defined by the -"bitfields" section. +"Integers" section. All basic types, except bitfields, are either aligned on an architecture-defined specific alignment or byte-packed, depending on the architecture preference. Architectures providing fast unaligned write byte-packed basic types to save space, aligning each type on byte boundaries (8-bit). Architectures with slow unaligned writes align types on specific alignment values. If no specific -alignment is declared for a type nor its parents, it is assumed to be bit-packed -for bitfields and byte-packed for other types. +alignment is declared for a type, it is assumed to be bit-packed for +integers with size not multiple of 8 bits and for gcc bitfields. All +other types are byte-packed. Metadata attribute representation of a specific alignment: @@ -274,10 +271,7 @@ this format by having the same start_value and end_value for each element, which is in fact a range of size 1. This single-value range is supported without repeating the start and end values with the value = string declaration. -If a numeric value is encountered between < >, it represents the integer type -size used to hold the enumeration, in bits. - -enum name { +enum name { somestring = start_value1 ... end_value1, "other string" = start_value2 ... end_value2, yet_another_string, /* will be assigned to end_value2 + 1 */ @@ -288,7 +282,7 @@ enum name { If the values are omitted, the enumeration starts at 0 and increment of 1 for each entry: -enum name <32> { +enum name { ZERO, ONE, TWO, @@ -374,7 +368,7 @@ variant name { }; struct { - enum { sel1, sel2, sel3, ... } tag_field; + enum { sel1, sel2, sel3, ... } tag_field; ... variant name v; } @@ -383,7 +377,7 @@ An unnamed variant definition within a structure is expressed by the following metadata: struct { - enum { sel1, sel2, sel3, ... } tag_field; + enum { sel1, sel2, sel3, ... } tag_field; ... variant { field_type sel1; @@ -765,20 +759,23 @@ contained within the payload. (This follows the ISO/C standard for structures) 7. Metadata -The meta-data is located in a stream named "metadata". It is made of "event -packets", which each start with an event packet header. The event type within -the metadata stream have no event header nor event context. Each event only -contains a null-terminated "string" payload, which is a metadata description -entry. The events are packed one next to another. Each event packet start with -an event packet header, which contains, amongst other fields, the magic number -and trace UUID. The trace UUID is represented as a string of hexadecimal digits -and dashes "-". - -The metadata can be parsed by reading through the metadata strings, skipping -newlines and null-characters. Type names are made of a single identifier, and -can be surrounded by prefix/postfix. Text contained within "/*" and "*/", as -well as within "//" and end of line, are treated as comments. Boolean values can -be represented as true, TRUE, or 1 for true, and false, FALSE, or 0 for false. +The meta-data is located in a stream identified by its name: "metadata". +It is made of "event packets", which each start with an event packet +header. The event type within the metadata stream have no event header +nor event context. Each event only contains a null-terminated "string" +payload, which is a metadata description entry. The events are packed +one next to another. Each event packet start with an event packet +header, which contains, amongst other fields, the magic number and trace +UUID. In the event packet header, the trace UUID is represented as an +array of bytes. Within the string-based metadata description, the trace +UUID is represented as a string of hexadecimal digits and dashes "-". + +The metadata can be parsed by reading through the metadata strings, +skipping null-characters. Type names are made of a single identifier, +and can be surrounded by prefix/postfix. Text contained within "/*" and +"*/", as well as within "//" and end of line, are treated as comments. +Boolean values can be represented as true, TRUE, or 1 for true, and +false, FALSE, or 0 for false. 7.1 Declaration vs Definition @@ -795,7 +792,8 @@ similarly to C99. The enumeration type specifier and variant tag name (both specified with "<" ">") are part of the type specifier. A definition associates a type to a location in the event structure -hierarchy (see Section 6). +hierarchy (see Section 6). This association is denoted by ":=", as shown +in Section 7.3. 7.2 Metadata Scopes @@ -853,7 +851,7 @@ consumption, for each event, the current trace context is therefore readable by accessing the upper dynamic scopes. -7.2 Metadata Examples +7.3 Metadata Examples The grammar representing the CTF metadata is presented in Appendix C. CTF Metadata Grammar. This section presents a rather ligher @@ -939,7 +937,7 @@ variant name { ... }; -enum name { +enum name { ... }; @@ -956,7 +954,7 @@ variant { ... } -enum { +enum { ... } @@ -1247,6 +1245,9 @@ unary-operator: one of assignment-operator: = +type-assignment-operator: + := + constant-expression: unary-expression @@ -1256,11 +1257,11 @@ constant-expression-range: 2.2) Declarations: declaration: - declaration-specifiers ; - declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ; + declaration-specifiers declarator-list-opt ; ctf-specifier ; declaration-specifiers: + storage-class-specifier declaration-specifiers-opt type-specifier declaration-specifiers-opt type-qualifier declaration-specifiers-opt @@ -1287,6 +1288,7 @@ type-specifier: unsigned _Bool _Complex + _Imaginary struct-specifier variant-specifier enum-specifier @@ -1333,9 +1335,6 @@ enum-specifier: enum identifier-opt < declaration-specifiers > { enumerator-list } enum identifier-opt < declaration-specifiers > { enumerator-list , } enum identifier < declaration-specifiers > - enum identifier-opt < integer-constant > { enumerator-list } - enum identifier-opt < integer-constant > { enumerator-list , } - enum identifier < integer-constant > enumerator-list: enumerator