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ETW/MsgPack: Chunk Span Start, Span Event, Span Stop as individual ET…
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…W events instead of consolidating in a single tree.

This is much more appropriate for heavily multi-threaded C++ apps, and provides predictable flow that may be subsequently
reconstructed / consolidated into a single tree of spans by out-of-proc listener agent, e.g. by Azure Diagnostics EventFlow.
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@maxgolov
maxgolov committed Mar 23, 2021
1 parent 4543a47 commit 48991c0
Showing 1 changed file with 26 additions and 73 deletions.
99 changes: 26 additions & 73 deletions exporters/etw/include/opentelemetry/exporters/etw/etw_provider.h
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Original file line number Diff line number Diff line change
Expand Up @@ -241,10 +241,10 @@ class ETWProvider
T eventData,
LPCGUID ActivityId = nullptr,
LPCGUID RelatedActivityId = nullptr,
uint8_t Opcode = 0 /* Information */)
uint8_t Opcode = 0)
{
#ifdef HAVE_MSGPACK
// Make sure you stop sending event before register unregistering providerData
// Events can only be sent if provider is registered
if (providerData.providerHandle == INVALID_HANDLE)
{
// Provider not registered!
Expand All @@ -254,6 +254,19 @@ class ETWProvider
std::string eventName = "NoName";
auto nameField = eventData[ETW_FIELD_NAME];

# ifdef HAVE_FIELD_TIME
// Event time is appended by ETW layer itself by default. This code allows
// to override the timestamp by millisecond timestamp, in case if it has
// not been already provided by the upper layer.
if (!eventData.count(ETW_FIELD_TIME))
{
// TODO: if nanoseconds resolution is required, then we can populate it in 96-bit MsgPack
// spec. auto nanos =
// std::chrono::duration_cast<std::chrono::nanoseconds>(now.time_since_epoch()).count();
eventData[ETW_FIELD_TIME] = opentelemetry::utils::getUtcSystemTimeMs();
}
# endif

switch (nameField.index())
{
case common::AttributeType::TYPE_STRING:
Expand All @@ -265,40 +278,15 @@ class ETWProvider
break;
# endif
default:
// This is user error. Invalid event name!
// We supply default 'NoName' event name in this case.
// If invalid event name is supplied, then we replace it with 'NoName'
break;
}

/* clang-format off */
nlohmann::json jObj =
{
{ ETW_FIELD_NAME, eventName },
{ ETW_FIELD_VERSION, "4.0" },
//
// TODO: compute time in MessagePack-friendly format
// TODO: should we consider uint64_t format with Unix timestamps for ELK stack?
{ ETW_FIELD_TIME,
{
// TODO: timestamp
{ "TypeCode", 255 },
{ "Body","0xFFFFFC60000000005F752C2C" }
}
},
#if 0
// TODO: follow JSON implementation of OTLP
{ "env_dt_traceId", "6dcdae7b9b0c7643967d74ee54056178" },
{ "env_dt_spanId", "5866c4322919e641" },
#endif
//
{ ETW_FIELD_KIND, 0 },
{ ETW_FIELD_STARTTIME,
{
// TODO: timestamp
{ "TypeCode", 255 },
{ "Body", "0xFFFF87CC000000005F752C2C" }
}
}
{ ETW_FIELD_KIND, Opcode }
};
/* clang-format on */

Expand Down Expand Up @@ -382,40 +370,7 @@ class ETWProvider
}
};

// Layer 1
nlohmann::json l1 = nlohmann::json::array();
// Layer 2
nlohmann::json l2 = nlohmann::json::array();
// Layer 3
nlohmann::json l3 = nlohmann::json::array();

l1.push_back("Span");

{
// TODO: clarify why this is needed
// TODO: fix time here
nlohmann::json j;
j["TypeCode"] = 255;
j["Body"] = "0xFFFFFC60000000005F752C2C";
l3.push_back(j);
};

// Actual value object goes here
l3.push_back(jObj);

l2.push_back(l3);
l1.push_back(l2);

{
// Another time field again, but at the top
// TODO: fix time here
nlohmann::json j;
j["TypeCode"] = 255;
j["Body"] = "0xFFFFFC60000000005F752C2C";
l1.push_back(j);
};

std::vector<uint8_t> v = nlohmann::json::to_msgpack(l1);
std::vector<uint8_t> v = nlohmann::json::to_msgpack(jObj);

EVENT_DESCRIPTOR evtDescriptor;
// TODO: event descriptor may be populated with additional values as follows:
Expand All @@ -428,17 +383,15 @@ class ETWProvider
EventDescCreate(&evtDescriptor, 0, 0x1, 0, 0, 0, Opcode, 0);
EVENT_DATA_DESCRIPTOR evtData[1];
EventDataDescCreate(&evtData[0], v.data(), static_cast<ULONG>(v.size()));

ULONG writeResponse = 0;

if ((ActivityId != nullptr) || (RelatedActivityId != nullptr))
{
EventWriteTransfer(providerData.providerHandle, &evtDescriptor, ActivityId, RelatedActivityId,
1, evtData);
writeResponse = EventWriteTransfer(providerData.providerHandle, &evtDescriptor, ActivityId,
RelatedActivityId, 1, evtData);
}
else
{
EventWrite(providerData.providerHandle, &evtDescriptor, 1, evtData);
writeResponse = EventWrite(providerData.providerHandle, &evtDescriptor, 1, evtData);
};

switch (writeResponse)
Expand Down Expand Up @@ -495,7 +448,7 @@ class ETWProvider
tld::EventMetadataBuilder<std::vector<BYTE>> builder(byteVector);
tld::EventDataBuilder<std::vector<BYTE>> dbuilder(byteDataVector);

const std::string EVENT_NAME = "name";
const std::string EVENT_NAME = ETW_FIELD_NAME;
std::string eventName = "NoName";
auto nameField = eventData[EVENT_NAME];
switch (nameField.index())
Expand Down Expand Up @@ -643,10 +596,10 @@ class ETWProvider
template <class T>
unsigned long write(Handle &providerData,
T eventData,
LPCGUID ActivityId = nullptr,
LPCGUID RelatedActivityId = nullptr,
uint8_t Opcode = 0, /* Information */
ETWProvider::EventFormat format = ETWProvider::EventFormat::ETW_MANIFEST)
LPCGUID ActivityId,
LPCGUID RelatedActivityId,
uint8_t Opcode,
ETWProvider::EventFormat format)
{
if (format == ETWProvider::EventFormat::ETW_MANIFEST)
{
Expand Down

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