Add support for conditional job execution

Performs a check before launching a job thread, rather than just having
it exit immediately.

2 files changed, 6 insertions, 2 deletions

diff --git a/src/ingestor.cpp b/src/ingestor.cpp
index fe8d38c..5f9fa60 100644
--- a/src/ingestor.cpp
+++ b/src/ingestor.cpp
@@ -426,7 +426,9 @@ namespace WebStat {
 				}
 			}
 			else if (expired(job.lastRun, freq, now)) {
-				job.currentRun.emplace(std::async(job.impl, this));
+				if (!job.cond || std::invoke(job.cond, this)) {
+					job.currentRun.emplace(std::async(job.impl, this));
+				}
 			}
 		};
 		runJobAsNeeded(ingestParkedLines, settings.freqIngestParkedLines);
diff --git a/src/ingestor.hpp b/src/ingestor.hpp
index dd803ce..a51c46c 100644
--- a/src/ingestor.hpp
+++ b/src/ingestor.hpp
@@ -46,10 +46,12 @@ namespace WebStat {
 			using LastRunTime = std::chrono::system_clock::time_point;
 			using Result = std::function<unsigned int()>;
 			using Impl = Result (Ingestor::*)();
+			using Cond = bool (Ingestor::*)();
 
-			explicit Job(Impl jobImpl) : impl(jobImpl) { }
+			explicit Job(Impl jobImpl, Cond jobCond = nullptr) : impl {jobImpl}, cond {jobCond} { }
 
 			const Impl impl;
+			const Cond cond;
 			LastRunTime lastRun {LastRunTime::clock::now()};
 			std::optional<std::future<Result>> currentRun;
 		};