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clockspec.cpp
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clockspec.cpp
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/* Copyright 2012-present Facebook, Inc.
* Licensed under the Apache License, Version 2.0 */
#include "watchman.h"
#include <folly/Synchronized.h>
#include <memory>
using namespace watchman;
static int proc_pid;
static uint64_t proc_start_time;
void ClockSpec::init() {
struct timeval tv;
proc_pid = (int)::getpid();
if (gettimeofday(&tv, NULL) == -1) {
logf(FATAL, "gettimeofday failed: {}\n", strerror(errno));
}
proc_start_time = (uint64_t)tv.tv_sec;
}
ClockSpec::ClockSpec(const json_ref& value) {
auto parseClockString = [=](const char* str) {
uint64_t start_time;
int pid;
uint32_t root_number;
uint32_t ticks;
// Parse a >= 2.8.2 version clock string
if (sscanf(
str,
"c:%" PRIu64 ":%d:%" PRIu32 ":%" PRIu32,
&start_time,
&pid,
&root_number,
&ticks) == 4) {
tag = w_cs_clock;
clock.start_time = start_time;
clock.pid = pid;
clock.position.rootNumber = root_number;
clock.position.ticks = ticks;
return true;
}
if (sscanf(str, "c:%d:%" PRIu32, &pid, &ticks) == 2) {
// old-style clock value (<= 2.8.2) -- by setting clock time and root
// number to 0 we guarantee that this is treated as a fresh instance
tag = w_cs_clock;
clock.start_time = 0;
clock.pid = pid;
clock.position.rootNumber = root_number;
clock.position.ticks = ticks;
return true;
}
return false;
};
switch (json_typeof(value)) {
case JSON_INTEGER:
tag = w_cs_timestamp;
timestamp = (time_t)value.asInt();
return;
case JSON_OBJECT: {
auto clockStr = value.get_default("clock");
if (clockStr) {
if (!parseClockString(json_string_value(clockStr))) {
throw std::domain_error("invalid clockspec");
}
} else {
tag = w_cs_clock;
clock.start_time = 0;
clock.pid = 0;
clock.position.rootNumber = 0;
clock.position.ticks = 0;
}
auto scm = value.get_default("scm");
if (scm) {
scmMergeBase = json_to_w_string(
scm.get_default("mergebase", w_string_to_json("")));
scmMergeBaseWith = json_to_w_string(scm.get("mergebase-with"));
auto savedState = scm.get_default("saved-state");
if (savedState) {
savedStateConfig = savedState.get("config");
savedStateStorageType = json_to_w_string(savedState.get("storage"));
auto commitId = savedState.get_default("commit-id");
if (commitId) {
savedStateCommitId = json_to_w_string(commitId);
} else {
savedStateCommitId = w_string();
}
}
}
return;
}
case JSON_STRING: {
auto str = json_string_value(value);
if (str[0] == 'n' && str[1] == ':') {
tag = w_cs_named_cursor;
named_cursor.cursor = json_to_w_string(value);
return;
}
if (parseClockString(str)) {
return;
}
/* fall through to default case and throw error.
* The redundant looking comment below is a hint to
* gcc that it is ok to fall through. */
}
/* fall through */
default:
throw std::domain_error("invalid clockspec");
}
}
std::unique_ptr<ClockSpec> ClockSpec::parseOptionalClockSpec(
const json_ref& value) {
if (value.isNull()) {
return nullptr;
}
return std::make_unique<ClockSpec>(value);
}
ClockSpec::ClockSpec() : tag(w_cs_timestamp), timestamp(0) {}
ClockSpec::ClockSpec(const ClockPosition& position)
: tag(w_cs_clock), clock{proc_start_time, proc_pid, position} {}
w_query_since ClockSpec::evaluate(
const ClockPosition& position,
const uint32_t lastAgeOutTick,
folly::Synchronized<std::unordered_map<w_string, uint32_t>>* cursorMap)
const {
w_query_since since;
switch (tag) {
case w_cs_timestamp:
// just copy the values over
since.is_timestamp = true;
since.timestamp = timestamp;
return since;
case w_cs_named_cursor: {
if (!cursorMap) {
// This is checked for and handled at parse time in SinceExpr::parse,
// so this should be impossible to hit.
throw std::runtime_error(
"illegal to use a named cursor in this context");
}
{
auto wlock = cursorMap->wlock();
auto& cursors = *wlock;
auto it = cursors.find(named_cursor.cursor);
if (it == cursors.end()) {
since.clock.is_fresh_instance = true;
since.clock.ticks = 0;
} else {
since.clock.ticks = it->second;
since.clock.is_fresh_instance = since.clock.ticks < lastAgeOutTick;
}
// record the current tick value against the cursor so that we use that
// as the basis for a subsequent query.
cursors[named_cursor.cursor] = position.ticks;
}
watchman::log(
watchman::DBG,
"resolved cursor ",
named_cursor.cursor,
" -> ",
since.clock.ticks,
"\n");
return since;
}
case w_cs_clock: {
if (clock.start_time == proc_start_time && clock.pid == proc_pid &&
clock.position.rootNumber == position.rootNumber) {
since.clock.is_fresh_instance = clock.position.ticks < lastAgeOutTick;
if (since.clock.is_fresh_instance) {
since.clock.ticks = 0;
} else {
since.clock.ticks = clock.position.ticks;
}
} else {
// If the pid, start time or root number don't match, they asked a
// different incarnation of the server or a different instance of this
// root, so we treat them as having never spoken to us before.
since.clock.is_fresh_instance = true;
since.clock.ticks = 0;
}
return since;
}
default:
throw std::runtime_error("impossible case in ClockSpec::evaluate");
}
}
bool clock_id_string(
uint32_t root_number,
uint32_t ticks,
char* buf,
size_t bufsize) {
int res = snprintf(
buf,
bufsize,
"c:%" PRIu64 ":%d:%u:%" PRIu32,
proc_start_time,
proc_pid,
root_number,
ticks);
if (res == -1) {
return false;
}
return (size_t)res < bufsize;
}
w_string ClockPosition::toClockString() const {
char clockbuf[128];
if (!clock_id_string(rootNumber, ticks, clockbuf, sizeof(clockbuf))) {
throw std::runtime_error("clock is too big for clockbuf");
}
return w_string(clockbuf, W_STRING_UNICODE);
}
/* Add the current clock value to the response */
void annotate_with_clock(
const std::shared_ptr<w_root_t>& root,
json_ref& resp) {
resp.set("clock", w_string_to_json(root->view()->getCurrentClockString()));
}
json_ref ClockSpec::toJson() const {
if (hasScmParams()) {
auto scm =
json_object({{"mergebase", w_string_to_json(scmMergeBase)},
{"mergebase-with", w_string_to_json(scmMergeBaseWith)}});
if (hasSavedStateParams()) {
auto savedState =
json_object({{"storage", w_string_to_json(savedStateStorageType)},
{"config", savedStateConfig}});
if (savedStateCommitId != w_string()) {
json_object_set(
savedState, "commit-id", w_string_to_json(savedStateCommitId));
}
json_object_set(scm, "saved-state", savedState);
}
return json_object({{"clock", w_string_to_json(position().toClockString())},
{"scm", scm}});
}
return w_string_to_json(position().toClockString());
}
bool ClockSpec::hasScmParams() const {
return scmMergeBase;
}
bool ClockSpec::hasSavedStateParams() const {
return savedStateStorageType;
}
/* vim:ts=2:sw=2:et:
*/